Provided by: libncarg-dev_6.6.2.dfsg.1-10build2_amd64 
NAME
Vectors_params - This document briefly describes all Vectors internal parameters.
DESCRIPTION
Parameter descriptions follow, in alphabetical order. Each description begins with a line giving the
three-character mnemonic name of the parameter, the phrase for which the mnemonic stands, the intrinsic
type of the parameter, and an indication of whether or not it is an array.
ACM - Arrow Color Mode - Integer
ACM controls how color is applied to filled vector arrows. It applies only when AST has the value
1. Its behavior also depends on the setting of the parameter CTV. Assuming that CTV is set to a
non-zero value, implying that multi-colored vectors are desired, ACM has the following settings:
Value Effect
----- ------
-2 Multi-colored fill; outline off
-1 Fill off; multi-colored outline
0 Multi-colored fill; mono-colored outline
1 Mono-colored fill; multi-colored outline
2 Multi-colored fill; multi-colored outline
Mono-colored outlines use the current GKS polyline color index. Mono-colored fill uses the current
GKS fill color index. When CTV is set to 0, both the fill and the outlines become mono-colored,
and therefore only modes -2, -1, and 0 remain distinguishable. The default value is 0.
AFO - Arrow Fill Over Arrow Lines - Integer
If AFO is set to 1, the perimeter outline of a filled vector arrow is drawn first, underneath the
fill. In this case, you must set the line thickness parameter (LWD) to a value greater than unity
in order for the line to appear completely. The advantage of drawing the line underneath is that
the full extent of the fill appears, resulting in a crisper, more sharply defined arrow; when the
line is drawn on top of the fill using a different color index, the fill color may be partially or
completely obscured, especially for small vector arrows. AFO has an effect only when the parameter
AST is set to 1. The default value of AFO is 1.
AIR - Arrow Interior Reference Fraction - Real
AIR specifies the distance from the point of the arrowhead of a filled vector arrow drawn at the
reference length to the point where the arrowhead joins with the line extending to the tail of the
arrow. Its value represents a fraction of the reference length. This distance is adjusted
proportionally to the X component of the arrowhead size for vector arrows whose length differs
from the reference length. See VRL for an explanation of how the reference length is determined.
AIR has an effect only when AST is set to 1. AIR is allowed to vary between 0.0 and 1.0 and its
default value is 0.33.
AMN - Arrow Head Minimum Size - Real
Specifies a minimum length for the two lines representing the point of the vector arrow head, as a
fraction of the viewport width. AMN has an effect only for line-drawn vector arrows (parameter AST
set to 0). Normally the arrow head size is scaled proportionally to the length of the vector. This
parameter allows you to ensure that the arrow head will remain recognizable even for very short
vectors. Note that you can cause all the arrowheads in the plot to be drawn at the same size if
you set AMN and AMX to the same value. If you set both AMN and AMX to 0.0 the arrowheads will not
be drawn at all. The default value is 0.005.
AMX - Arrow Head Maximum Size - Real
Specifies a maximum length for the two lines representing the point of the vector arrow head, as a
fraction of the viewport width. AMX has an effect only for line-drawn vector arrows (parameter
AST set to 0). Normally the arrow head is scaled proportionally to the length of the vector. This
parameter allows you to ensure that the arrow heads do not become excessively large for high
magnitude vectors. Note that you can cause all the arrowheads in the plot to be drawn at the same
size if you set AMN and AMX to the same value. If you set both AMN and AMX to 0.0 the arrowheads
will not be drawn at all. The default value is 0.05.
AST - Arrow Style - Integer
If AST is set to 0, the vector arrows are drawn using lines only. When AST is set to 1, the
vectors are plotted using variable width filled arrows, with an optional outline. If AST is set to
2, wind barb glyphs are used to represent the vectors.There are parameters for controlling the
appearance of each style. These have an effect only for one value of AST. However, certain
parameters apply to all arrow styles. Here is a table of parameters that affect the appearance of
vectors and how their behavior is affected by the setting of AST:
Parameter Line-Drawn Arrows Filled Arrows Wind Barbs
--------- ----------------- ------------- ----------
ACM x
AFO x
AIR x
AMN x
AMX x
AWF x
AWR x
AXF x
AXR x
AYF x
AYR x
CLR x x x
CTV x x x
LWD x x x
NLV x x x
PAI x x x
TVL x x x
WBA x
WBC x
WBD x
WBS x
WBT x
When filled arrows are used, colors associated with the threshold levels may be applied to either
or both the fill or the outline of the arrow. When fill is drawn over the outline (AFO set to 1),
LWD should be set to a value greater than 1.0 in order for the outline to be fully visible. The
default value of AST is 0.
AWF - Arrow Width Fractional Minimum - Real
AWF specifies the width of a filled arrow drawn at the minimum length, as a fraction of the width
of an arrow drawn at the reference length. If AWF has the value 0.0, then the ratio of the arrow
width to the arrow length will be constant for all arrows in the plot. If given the value 1.0,
the width will itself be constant for all arrows in the plot, regardless of length. See VFR for a
discussion of how the minimum length is determined. AWF has an effect only when AST is set to 1.
AWF is allowed to vary between 0.0 and 1.0 and its default value is 0.0.
AWR - Arrow Width Reference Fraction - Real
AWR specifies the width of a filled vector arrow drawn at the reference length, as a fraction of
the reference length. See VRL for an explanation of how the reference length is determined. AWR
has an effect only when AST is set to 1. AWR is allowed to vary between 0.0 and 1.0 and its
default value is 0.03.
AXF - Arrow X-Coord Fractional Minimum - Real
AXF specifies the X component of the head of a filled vector arrow drawn at the minimum length, as
a fraction of the X component of the head of an arrow drawn at the reference length. The X
component of the arrowhead is the distance from the point of the arrowhead to a point along the
centerline of the arrow perpendicular the arrowhead´s rear tips. If AXF has the value 0.0, then
the ratio of the X component of the arrowhead size to the arrow length will be constant for all
vectors in the plot. If given the value 1.0, the arrowhead X component will itself be constant for
all arrows in the plot, regardless of their length. See VRL for an explanation of how the
reference length is determined. AXF has an effect only when AST is set to 1. AXF is allowed to
vary between 0.0 and 1.0 and its default value is 0.0.
AXR - Arrow X-Coord Reference Fraction - Real
AXR specifies the X component of the head of a filled vector arrow drawn at the reference length,
as a fraction of reference length. The X component of the arrowhead is the distance from the point
of the arrowhead to a point along the centerline of the arrow perpendicular the arrowhead´s rear
tips. See VRL for an explanation of how the reference length is determined. AXR has an effect
only when AST is set to 1. AXR is allowed to vary between 0.0 and 2.0 and its default value is
0.36.
AYF - Arrow Y-Coord Fractional Minimum - Real
The value of this parameter, when added to the minimum width value, specifies the Y component
length of the arrowhead size for a filled arrow drawn at the minimum length, as a fraction of the
length specified by AYF. If given the value 1.0, the arrowhead Y component will extend the same
distance perpendicularly from the edge of all arrows in the plot, regardless of their length and
width. This can be a useful resource to adjust to ensure that the points of even very short vector
arrows remain visible. See VFR for a discussion of how the minimum length is determined. AYF has
an effect only when AST is set to 1. AYF is allowed to vary between 0.0 and 1.0 and its default
value is 0.25.
AYR - Arrow Y-Coord Reference Fraction - Real
AYR specifies the perpendicular distance from one side of a filled vector arrowdrawn at the
reference length to one of the back tips of the arrowhead. The value represents a fraction of the
value of of the reference length and, when added to half the arrow width, determines the Y
component of the arrowhead size. See VRL for an explanation of how the reference length is
determined. AYR has an effect only when AST is set to 1. AYR is allowed to vary between 0.0 and
1.0 and its default value is 0.12.
CLR - Array of GKS Color Indices - Integer Array
This parameter represents an array containing the GKS color index to use for coloring the vector
when the scalar quantity is less than or equal to the threshold value with the same index in the
TVL threshold value array. Depending on the settings of AST and ACM it may specify a set of fill
color indexes, a set of line color indexes, or both. In order to access a particular element of
the CLR array, you must first set the value of PAI, the parameter array index parameter, to the
value of the array element´s index. All elements of the array are set to one initially. Note that
the Vectors utility makes no calls to set the GKS color representation (GSCR), nor ever modifies
the contents of the CLR array; therefore you are responsible for creating a suitably graduated
color palette and assigning the color index values into the CLR array, prior to calling VVECTR.
Typically, assuming the desired RGB values have been previously stored in a 2 dimensional 3 x n
array called RGB, you loop through the calls that set up the color representation and color index
as in the following example for a fourteen color palette:
DO 100 I=1,14,1
CALL GSCR (1,I,RGB(1,I),RGB(2,I),RGB(3,I))
CALL VVSETI(´PAI -- Parameter Array Index´, I)
CALL VVSETI(´CLR -- GKS Color Index´, I)
100 CONTINUE
See the descriptions of CTV, NLV, and TVL for details on configuring the vector coloring scheme.
CPM - Compatibility Mode - Integer
Controls the degree of compatibility between pre-Version 3.2 capabilities of the Vectors utility
and later versions. You can independently control three behaviors using the nine settings
provided:
• use of VELVCT and VELVEC input parameters
• use of variables initialized in the VELDAT block data statement
• use of the old mapping routines, FX, FY, MXF, and MYF.
Note, however, that when using the Version 3.2 entry points VVINIT and VVECTR, only the third
behavior option has any meaning.
When CPM is set to 0, its default value, the Vectors utility´s behavior varies depending on
whether you access it through one of the pre-Version 3.2 entry points (VELVCT, VELVEC, and EZVEC),
or through the VVINIT/VVECTR interface. Otherwise, positive values result in invocation of the
pre-Version 3.2 mapping routines (FX, FY, MXF, and MYF) for the conversion from data to user
coordinates. Negative values cause VVMPXY or perhaps VVUMXY to be used instead. When using the
pre-Version 3.2 interface, odd values of CPM cause the data values in the VELDAT block data
subroutine to override corresponding values initialized in the Version 3.2 VVDATA block data
subroutine, or set by the user calling VVSETx routines. Values of CPM with absolute value greater
than two cause some of the input arguments to VELVEC and VELVCT to be ignored. These include FLO,
HI, NSET, ISPV, SPV and (for VELVCT only) LENGTH.
Here is a table of the nine settings of CPM and their effect on the operation of the Vectors
utility:
Value Use FX, FY, etc. Use VELDAT data Use input args
----- ---------------- --------------- --------------
-4 no no no
-3 no yes no
-2 no no yes
-1 no yes yes
0 old - yes; new - no (*) yes yes
1 yes yes yes
2 yes no yes
3 yes yes no
4 yes no no
(*) Old means EZVEC, VELVEC, VELVCT entry point; new, VVINIT/VVECTR. Only the first column
applies to the VVINIT/VVECTR interface. See the velvct man page for more detailed emulation
information.
CTV - Color Threshold Value Control - Integer
In conjunction with NLV, this parameter controls vector coloring and the setting of threshold
values. The vectors may be colored based on on the vector magnitude or on the contents of a scalar
array (VVINIT/VVECTR input argument, P). A table of supported options follows:
Value Action
-2 Color vector arrows based on scalar array data values; the user is responsible for
setting up threshold level array, TVL
-1 Color vector arrows based on vector magnitude; the user is responsible for setting
up values of threshold level array.
0(default) Color all vectors according to the current GKS polyline color index value.
Threshold level array, TVL and GKS color index array, CLR are not used.
1 Color vector arrows based on vector magnitude; VVINIT assigns values to the first
NLV elements of the threshold level array, TVL.
2 Color vector arrows based on scalar array data values; VVINIT assigns values to the
first NLV elements of the threshold level array, TVL.
If you make CTV positive, you must initialize Vectors with a call to VVINIT after the
modification.
DMN - NDC Minimum Vector Size - Real, Read-Only
This parameter is read-only and has a useful value only following a call to VVECTR (directly or
through the compatibility version of VELVCT). You may retrieve it in order to determine the length
in NDC space of the smallest vector actually drawn (in other words, the smallest vector within the
boundary of the user coordinate space that is greater than or equal in magnitude to the value of
the VLC parameter). It is initially set to a value of 0.0.
DMX - NDC Maximum Vector Size - Real, Read-Only
Unlike DMN this read-only parameter has a potentially useful value betweens calls to VVINIT and
VVECTR. However, the value it reports may be different before and after the call to VVECTR. Before
the VVECTR call it contains the length in NDC space that would be used to render the maximum size
vector assuming the user-settable parameter, VRL is set to its default value of 0.0. After the
VVECTR call it contains the NDC length used to render the largest vector actually drawn (in other
words, the largest vector within the boundary of the user coordinate space that is less than or
equal in magnitude to the value of the VHC parameter). See the section on the VRL parameter for
information on using the value of DMX after the VVINIT call in order to adjust proportionally the
lengths of all the vectors in the plot. It is initially set to a value of 0.0.
DPF - Vector Label Decimal Point Control Flag - Integer
If DPF is set to a non-zero value, and the optional vector magnitude labels are enabled, the
magnitude values are scaled to fit in the range 1 to 999. The labels will contain 1 to 3 digits
and no decimal point. Otherwise, the labels will consist of a number up to six characters long,
including a decimal point. By default DPF is set to the value 1.
LBC - Vector Label Color - Integer
This parameter specifies the color to use for the optional vector magnitude labels, as follows:
Value Action
< -1 Draw labels using the current GKS text color index
-1 (default) Draw labels using the same color as the corresponding vector arrow
>=0 Draw labels using the LBC value as the GKS text color index
LBL - Vector Label Flag - Integer
If set non-zero, Vectors draws labels representing the vector magnitude next to each arrow in the
field plot. The vector labels are primarily intended as a debugging aid, since in order to avoid
excessive overlap, you must typically set the label text size too small to be readable without
magnification. For this reason, as well as for efficiency, unlike the other graphical text
elements supported by the Vectors utility, the vector labels are rendered using low quality text.
LBS - Vector Label Character Size - Real
This parameter specifies the size of the characters used for the vector magnitude labels as a
fraction of the viewport width. The default value is 0.007.
LWD - Vector Linewidth - Real
LWD controls the linewidth used to draw the lines that form vector arrows and wind barbs. When the
arrows are filled (AST is set to 1) LWD controls the width of the arrow's outline. If the fill is
drawn over the outline (AFO set to 1) then LWD must be set to a value greater than 1.0 in order
for the outline to appear properly. When AST has the value 2, LWD controls the width of the line
elements of wind barbs. When AST is set to 0, specifying line-drawn vector arrows, the linewidth
applies equally to the body of the vector and the arrowhead. Overly thick lines may cause the
arrow heads to appear smudged. This was part of the motivation for developing the option of filled
vector arrows. Note that since linewidth in NCAR Graphics is always calculated relative to a unit
linewidth that is dependent on the output device, you may need to adjust the linewidth value
depending on the intended output device to obtain a pleasing plot. The default is 1.0, specifying
a device-dependent minimum linewidth.
MAP - Map Transformation Code - Integer
MAP defines the transformation between the data and user coordinate space. Three MAP parameter
codes are reserved for pre-defined transformations, as follows:
Value Mapping transformation
0 (default) Identity transformation between data and user coordinates: array indices of U, V,
and P are linearly related to data coordinates.
1 Ezmap transformation: first dimension indices of U, V, and P are linearly related
to longitude; second dimension indices are linearly related to latitude.
2 Polar to rectangular transformation: first dimension indices of U, V, and P are
linearly related to the radius; second dimension indices are linearly related to
the angle in degrees.
If MAP has any other value, Vectors invokes the user-modifiable subroutine, VVUMXY, to perform the
mapping. The default version of VVUMXY simply performs an identity transformation. Note that,
while the Vectors utility does not actually prohibit the practice, the user is advised not to use
negative integers for user-defined mappings, since other utilities in the NCAR Graphics toolkit
attach a special meaning to negative mapping codes.
For all the predefined mappings, the linear relationship between the grid array indices and the
data coordinate system is established using the four parameters, XC1, XCM, YC1, and YCN. The X
parameters define a mapping for the first and last indices of the first dimension of the data
arrays, and the Y parameters do the same for the second dimension. If MAP is set to a value of
one, be careful to ensure that the SET parameter is given a value of zero, since the Ezmap
routines require a specific user coordinate space for each projection type, and internally call
the SET routine to define the user to NDC mapping. Otherwise, you may choose whether or not to
issue a SET call prior to calling VVINIT, modifying the value of SET as required. See the
description of the parameter, TRT, and the vvumxy man page for more information.
MNC - Minimum Vector Text Block Color - Integer
MNC specifies the color of the minimum vector graphical text output block as follows:
Value Action
<-2 Both the vector arrow and the text are colored using the current text color index.
-2 If the vectors are colored by magnitude, both the vector arrow and the text use the
GKS color index associated with the minimum vector magnitude. Otherwise, the vector
arrow uses the current polyline color index and the text uses the current text
color index.
-1 (default) If the vectors are colored by magnitude, the vector arrow uses the GKS color index
associated with the minimum vector magnitude. Otherwise the vector arrow uses the
current polyline color index. The text is colored using the current text color
index in either case.
>= 0 The value of MNC is used as the color index for both the text and the vector arrow
See the description of MNT for more information about the minimum vector text block.
MNP - Minimum Vector Text Block Positioning Mode - Integer
This parameter allows you to justify the minimum vector text block, taken as a single unit,
relative to the text block position established by the parameters, MNX and MNY. Nine positioning
modes are available, as follows:
Mode Justification
-4 The lower left corner of the text block is positioned at MNX, MNY.
-3 The center of the bottom edge is positioned at MNX, MNY.
-2 The lower right corner is positioned at MNX, MNY.
-1 The center of the left edge is positioned at MNX, MNY.
0 The text block is centered along both axes at MNX, MNY.
1 The center of the right edge is positioned at MNX, MNY.
2 The top left corner is positioned at MNX, MNY.
3 The center of the top edge is positioned at MNX, MNY.
4 (default) The top right corner is positioned at MNX, MNY.
See the description of MNT for more information about the minimum vector text block.
MNS - Minimum Vector Text Block Character Size - Real
MNS specifies the size of the characters used in the minimum vector graphics text block as a
fraction of the viewport width. See the description of MNT for more information about the minimum
vector text block. The default value of MNS is 0.0075.
MNT - Minimum Vector Text String - Character* 36
The minimum vector graphics text block consists of a user-definable text string centered
underneath a horizontal arrow. If the parameter VLC is set negative the arrow is rendered at the
size of the reference minimum magnitude vector (which may be smaller than any vector that actually
appears in the plot). Otherwise, the arrow is the size of the smallest vector in the plot.
Directly above the arrow is a numeric string in exponential format that represents the vector's
magnitude.
Use MNT to modify the text appearing below the vector in the minimum vector graphics text block.
Currently the string length is limited to 36 characters. Set MNT to a single space (´ ´) to remove
the text block, including the vector arrow and the numeric magnitude string, from the plot. The
default value is ´Minimum Vector´
MNX - Minimum Vector Text Block X Coordinate - Real
MNX establishes the X coordinate of the minimum vector graphics text block as a fraction of the
viewport width. Values less than 0.0 or greater than 1.0 are permissible and respectively
represent regions to the left or right of the viewport. The actual position of the block relative
to MNX depends on the value assigned to MNP. See the descriptions of MNT and MNP for more
information about the minimum vector text block. The default value of MNX is 0.475.
MNY - Minimum Vector Text Block Y Coordinate - Real
MNY establishes the Y coordinate of the minimum vector graphics text block as a fraction of the
viewport height. Values less than 0.0 or greater than 1.0 are permissible and respectively
represent regions below or above the viewport. The actual position of the block relative to MNY
depends on the value assigned to MNP. See the descriptions of MNT and MNP for more information
about the minimum vector text block. The default value of MNY is -0.01.
MSK - Mask To Area Map Flag - Integer
Use this parameter to control masking of vectors to an existing area map created by routines in
the Areas utility. When MSK is greater than 0, masking is enabled and an the area map must be set
up prior to the call to VVECTR. The area map array and, in addition, the name of a user-definable
masked drawing routine, must be passed as input parameters to VVECTR. Various values of the MSK
parameter have the following effects:
Value Effect
<= 0 (default) No masking of vectors.
1 The subroutine ARDRLN is called internally to decompose the vectors into segments
contained entirely within a single area. ARDRLN calls the user-definable masked
drawing subroutine.
>1 Low precision masking. ARGTAI is called internally to get the area identifiers for
the vector base position point. Then the user-definable masked drawing subroutine
is called to draw the vector. Vectors with nearby base points may encroach into the
intended mask area.
See the man page vvudmv for further explanation of masked drawing of vectors
MXC - Maximum Vector Text Block Color - Integer
MXC specifies the color of the maximum vector graphical text output block as follows:
Value Action
<-2 Both the vector arrow and the text are colored using the current text color index.
-2 If the vectors are colored by magnitude, both the vector arrow and the text use the
GKS color index associated with the minimum vector magnitude. Otherwise, the vector
arrow uses the current polyline color index and the text uses the current text
color index.
-1 (default) If the vectors are colored by magnitude, the vector arrow uses the GKS color index
associated with the minimum vector magnitude. Otherwise the vector arrow uses the
current polyline color index. The text is colored using the current text color
index in either case.
>= 0 The value of MXC is used as the color index for both the text and the vector arrow
See the description of MXT for more information about the maximum vector text block.
MXP - Maximum Vector Text Block Positioning Mode - Integer
This parameter allows you to justify the maximum vector text block, taken as a single unit,
relative to the text block position established by the parameters, MXX and MXY. Nine positioning
modes are available, as follows:
Mode Justification
-4 The lower left corner of the text block is positioned at MXX, MXY.
-3 The center of the bottom edge is positioned at MXX, MXY.
-2 The lower right corner is positioned at MXX, MXY.
-1 The center of the left edge is positioned at MXX, MXY.
0 The text block is centered along both axes at MXX, MXY.
1 The center of the right edge is positioned at MXX, MXY.
2 The top left corner is positioned at MXX, MXY.
3 The center of the top edge is positioned at MXX, MXY.
4 The top right corner is positioned at MXX, MXY.
See the description of MXT for more information about the maximum vector text block.
MXS - Maximum Vector Text Block Character Size - Real
MXS specifies the size of the characters used in the maximum vector graphics text block as a
fraction of the viewport width. See the description of MXT for more information about the maximum
vector text block. The default value is 0.0075.
MXT - Maximum Vector Text String - Character* 36
The maximum vector graphics text block consists of a user-definable text string centered
underneath a horizontal arrow. If the parameter VHC is set negative the arrow is rendered at the
size of the reference maximum magnitude vector (which may be larger than any vector that actually
appears in the plot). Otherwise, the arrow is the size of the largest vector in the plot. Directly
above the arrow is a numeric string in exponential format that represents the magnitude of this
vector.
Use MXT to modify the text appearing below the vector in the maximum vector graphics text block.
Currently the string length is limited to 36 characters. Set MXT to a single space (´ ´) to
completely remove the text block, including the vector arrow and the numeric magnitude string,
from the plot. Note that the name "Maximum Vector Text Block" is no longer accurate, since using
the parameter VRM it is now possible to establish a reference magnitude that is smaller than the
maximum magnitude in the data set. A more accurate name would be "Reference Vector Text Block".
The default value of MXT is ´Maximum Vector´.
MXX - Maximum Vector Text Block X Coordinate - Real
MXX establishes the X coordinate of the maximum vector graphics text block as a fraction of the
viewport width. Values less than 0.0 or greater than 1.0 are permissible and respectively
represent regions below or above of the viewport. The actual position of the block relative to MXX
depends on the value assigned to MXP. See the descriptions of MXT and MXP for more information
about the maximum vector text block. The default value is 0.525.
MXY - Maximum Vector Text Block Y Coordinate - Real
MXY establishes the Y coordinate of the maximum vector graphics text block as a fraction of the
viewport width. Values less than 0.0 or greater than 1.0 are permissible and respectively
represent regions below or above the viewport. The actual position of the block relative to MXY
depends on the value assigned to MXP. See the descriptions of MXT and MXP for more information
about the maximum vector text block. The default value is -0.01.
NLV - Number of Colors Levels - Integer
NLV specifies the number of color levels to use when coloring the vectors according to data in a
scalar array or by vector magnitude. Anytime CTV has a non-zero value, you must set up the first
NLV elements of the color index array CLR. Give each element the value of a GKS color index that
must be defined by a call to the the GKS subroutine, GSCR, prior to calling VVECTR. If CTV is less
than 0, in addition to setting up the CLR array, you are also responsible for setting the first
NLV elements of the threshold values array, TVL to appropriate values. NLV is constrained to a
maximum value of 255. The default value of NLV is 0, specifying that vectors are colored according
to the value of the GKS polyline color index currently in effect, regardless of the value of CTV.
If CTV is greater than 0, you must initialize Vectors with a call to VVINIT after modifying this
parameter.
PAI - Parameter Array Index - Integer
The value of PAI must be set before calling VVGETC, VVGETI, VVGETR, VVSETC, VVSETI, or VVSETR to
access any parameter which is an array; it acts as a subscript to identify the intended array
element. For example, to set the 10th color threshold array element to 7, use code like this:
CALL VVSETI (´PAI - PARAMETER ARRAY INDEX´,10)
CALL VVSETI (´CLR - Color Index´,7)
The default value of PAI is one.
PLR - Polar Input Mode - Integer
When PLR is greater than zero, the vector component arrays are considered to contain the field
data in polar coordinate form: the U array is treated as containing the vector magnitude and the V
array as containing the vector angle. Be careful not to confuse the PLR parameter with the MAP
parameter set to polar coordinate mode (2). The MAP parameter relates to the location of the
vector, not its value. Here is a table of values for PLR:
Value Meaning
0 (default) U and V arrays contain data in cartesian component form.
1 U array contains vector magnitudes; V array contains vector angles in degrees.
2 U array contain vector magnitudes; V array contains vector angles in radians.
You must initialize Vectors with a call to VVINIT after modifying this parameter.
PMN - Minimum Scalar Array Value - Real, Read-Only
You may retrieve the value specified by PMN at any time after a call to VVINIT. It will contain a
copy of the minimum value encountered in the scalar data array. If no scalar data array has been
passed into VVINIT it will have a value of 0.0.
PMX - Maximum Scalar Array Value - Real
You may retrieve the value specified by PMX at any time after a call to VVINIT. It contains a copy
of the maximum value encountered in the scalar data array. If no scalar data array has been
passed into VVINIT it will have a value of 0.0.
PSV - P Array Special Value - Real
Use PSV to indicate the special value that flags an unknown data value in the P scalar data array.
This value will not be considered in the determination of the data set maximum and minimum values.
Also, depending on the setting of the SPC parameter, the vector may be specially colored to flag
the unknown data point, or even eliminated from the plot. You must initialize Vectors with a call
to VVINIT after modifying this parameter.
SET - SET Call Flag - Integer
Give SET the value 0 to inhibit the SET call VVINIT performs by default. Arguments 5-8 of a SET
call made by the user must be consistent with the ranges of the user coordinates expected by
Vectors. This is determined by the mapping from grid to data coordinates as specified by the
values of the parameters XC1, XCM, YC1, YCN, and also by the mapping from data to user coordinates
established by the MAP parameter. You must initialize Vectors with a call to VVINIT after
modifying this parameter. The default value of SET is 1.
SPC - Special Color - Integer
SPC controls special value processing for the optional scalar data array used to color the
vectors, as follows:
Value Effect
< 0 (default) The P scalar data array is not examined for special values.
0 Vectors at P scalar array special value locations are not drawn.
> 0 Vectors at P scalar array special value locations are drawn using color index SPC.
You must initialize Vectors with a call to VVINIT after modifying this parameter.
SVF - Special Value Flag - Integer
The special value flag controls special value processing for the U and V vector component data
arrays. Special values may appear in either the U or V array or in both of them. Five different
options are available (although the usefulness of some of the choices is debatable):
Value Effect
0 (default) Neither the U nor the V array is examined for special values
1 Vectors with special values in the U array are not drawn
2 Vectors with special values in the V array are not drawn
3 Vectors with special values in either the U or V array are not drawn
4 Vectors with special values in both the U and V arrays are not drawn
The U and V special values are defined by setting parameters USV and VSV. You must initialize
Vectors with a call to VVINIT after modifying this parameter.
TRT - Transformation Type - Integer
As currently implemented, TRT further qualifies the mapping transformation specified by the MAP
parameter, as follows:
Value Effect
-1 Direction, magnitude, and location are all transformed. This option is not
currently supported by any of the pre-defined coordinate system mappings.
0 Only location is transformed
1 (default) Direction and location are transformed
This parameter allows you to distinguish between a system that provides a mapping of location only
into an essentially cartesian space, and one in which the space itself mapped. To understand the
difference, using polar coordinates as an example, imagine a set of wind speed monitoring units
located on a radial grid around some central point such as an airport control tower. Each unit´s
position is defined in terms of its distance from the tower and its angular direction from due
east. However, the data collected by each monitoring unit is represented as conventional eastward
and northward wind components. Assuming the towers´s location is at a moderate latitude, and the
monitoring units are reasonably ´local´, this is an example of mapping a radially defined location
into a nearly cartesian space (i.e. the eastward components taken alone all point in a single
direction on the plot, outlining a series of parallel straight lines). One would set MAP to two
(for the polar transformation) and TRT to zero to model this data on a plot generated by the
Vectors utility.
On the other hand, picture a set of wind data, again given as eastward and northward wind
components, but this time the center of the polar map is actually the south pole. In this case,
the eastward components do not point in a single direction; instead they outline a series of
circles around the pole. This is a space mapping transformation: one would again set MAP to two,
but TRT would be set to one to transform both direction and location.
Changing the setting of this parameter affects the end results only when a non-uniform non-linear
mapping occurs at some point in the transformation pipeline. For this discussion a uniform linear
transformation is defined as one which satisfies the following equations:
x_out = x_offset + scale_constant * x_in
y_out = y_offset + scale_constant * y_in
If scale_constant is not the same for both the X axis and the Y axis then the mapping is non-
uniform.
This option is currently implemented only for the pre-defined MAP parameter codes, 0 and 2, the
identity mapping and the polar coordinate mapping. However, it operates on a different stage of
the transformation pipeline in each case. The polar mapping is non-linear from data to user
coordinates. The identity mapping, even though necessarily linear over the data to user space
mapping, can have a non-uniform mapping from user to NDC space, depending on the values given to
the input parameters of the SET call. This will be the case whenever the LL input parameter is
other than one, or when LL equals one, but the viewport and the user coordinate boundaries do not
have the same aspect ratio. Thus for a MAP value of 2, TRT affects the mapping between data and
user space, whereas for MAP set to 0, TRT influences the mapping between user and NDC space.
TVL - Array of Threshold Values - Real Array
TVL is an array of threshold values that is used to determine the individual vector color, when
CTV and NLV are both non-zero. For each vector the TVL array is searched for the smallest value
greater than or equal to the scalar value associated with the vector. The array subscript of this
element is used as an index into the CLR array. Vectors uses the GKS color index found at this
element of the CLR array to set the color for the vector. Note that Vectors assumes that the
threshold values are monotonically increasing.
When CTV is less than 0, you are responsible for assigning values to the elements of TVL yourself.
To do this, first set the PAI parameter to the index of the threshold level element you want to
define, then call VVSETR to set TVL to the appropriate threshold value for this element. Assuming
the desired values have previously been stored in a array named TVALS, you could assign the
threshold values for a fourteen level color palette using the following loop:
DO 100 I=1,14,1
CALL VVSETI(PAI -- Parameter Array Index, I)
CALL VVSETR(TVL -- Threshold Value, TVALS(I))
100 CONTINUE
When CTV is greater than 0, Vectors assigns values into TVL itself. Each succeeding element value
is greater than the preceding value by the value of the expression:
(maximum_data_value - minimum_data_value) / NLV
where the data values are either from the scalar data array or are the magnitudes of the vectors
in the vector component arrays. The first value is equal to the minimum value plus the expression;
the final value (indexed by the value of NLV) is equal to the maximum value. If Vectors encounters
a value greater than the maximum value in the TVL array while processing the field data, it gives
the affected vector the color associated with the maximum TVL value.
USV - U Array Special Value - Real
USV is the U vector component array special value. It is a value outside the range of the normal
data used to indicate that there is no valid data for this grid location. When SVF is set to 1 or
3, Vectors will not draw a vector whose U component has the special value. You must initialize
Vectors with a call to VVINIT after modifying this parameter. It has a default value of 1.0 E12.
VFR - Minimum Vector Fractional Length - Real
Use this parameter to adjust the realized size of the reference minimum magnitude vector relative
to the reference maximum magnitude vector in order to improve the appearance or perhaps the
information content of the plot. Specify VFR as a value between 0.0 and 1.0, where 0.0 represents
an unmodified linear scaling of the realized vector length, in proportion to magnitude, and 1.0
specifies that the smallest vector be represented at 1.0 times the length of the largest vector,
resulting in all vectors, regardless of magnitude, having the same length on the plot. A value of
0.5 means that the smallest magnitude vector appears half as long as the largest magnitude vector;
intermediate sizes are proportionally scaled to lengths between these extremes. Where there is a
wide variation in magnitude within the vector field, you can use this parameter to increase the
size of the smallest vectors to a usefully visible level. Where the variation is small, you can
use the parameter to exaggerate the differences that do exist. See also the descriptions of VRL,
VLC, VHC, and VRM. The default value is 0.0.
VHC - Vector High Cutoff Value - Real
If the parameter VRM is set to a value greater than 0.0, it supercedes the use of VHC to specify
the reference magnitude. VRM allows greater flexibility in that it can be used to specify an
arbitrary reference magnitude that need not be the maximum magnitude contained in the data set.
VHC can still be used to set a high cutoff value -- no vectors with magnitude greater than the
cutoff value will be displayed in the plot.
If VRM has its default value, 0.0, VHC specifies the reference maximum magnitude represented by an
arrow of length VRL (as a fraction of the viewport width). The realized length of each individual
vector in the plot is based on its magnitude relative to the reference maximum magnitude and, if
VFR is non-zero, the reference minimum magnitude (as specified by VLC). Note that the reference
maximum magnitude may be greater than the magnitude of any vector in the dataset. The effect of
this parameter varies depending on its value, as follows:
Value Effect
< 0.0 The absolute value of VHC unconditionally determines the reference maximum
magnitude. Vectors in the dataset with magnitude greater than VHC are not
displayed.
0.0 (default) The vector with the greatest magnitude in the dataset determines the reference
maximum magnitude.
> 0.0 The minimum of VHC and the vector with the greatest magnitude in the data set
determines the reference maximum magnitude. Vectors in the dataset with magnitude
greater than VHC are not displayed.
Typically, for direct comparison of the output of a series of plots, you would set VHC to a
negative number, the absolute value of which is greater than any expected vector magnitude in the
series. You can turn on Vectors statistics reporting using the parameter VST in order to see if
any vectors in the datasets do exceed the maximum magnitude you have specified. See also the
descriptions of the parameters VRM, VRL, DMX, VLC, and VFR.
VLC - Vector Low Cutoff Value - Real
Use this parameter to prevent vectors smaller than the specified magnitude from appearing in the
output plot. VLC also specifies the reference minimum magnitude that is rendered at the size
specified by the product of VRL and VFR (as a fraction of the viewport width), when VFR is greater
than 0.0. Note that the reference minimum magnitude may be smaller than the magnitude of any
vector in the dataset. The effect of this parameter varies depending on its value, as follows:
Value Effect
< 0.0 The absolute value of VLC unconditionally determines the reference minimum
magnitude. Vectors in the dataset with magnitude less than VLC do not appear.
0.0 (default) The vector with the minimum magnitude in the dataset determines the reference
minimum magnitude.
> 0.0 The maximum of VLC and the vector with the least magnitude in the data set
determines the reference minimum magnitude. Vectors in the dataset with magnitude
less than VLC do not appear.
The initialization subroutine, VVINIT, calculates the magnitude of all the vectors in the vector
field, and stores the maximum and minimum values. You may access these values by retrieving the
read-only parameters, VMX and VMN. Thus it is possible to remove the small vectors without prior
knowledge of the data domain. The following code fragment illustrates how the smallest 10% of the
vectors could be removed:
CALL VVINIT(...
CALL VVGETR(´VMX - Vector Maximum Magnitude´, VMX)
CALL VVGETR(´VMN - Vector Minimum Magnitude´, VMN)
CALL VVSETR(´VLC - Vector Low Cutoff Value´,
+ VMN+0.1*(VMX-VMN))
CALL VVECTR(...
On the other hand, when creating a series of plots that you would like to compare directly and you
are using VFR to set a minimum realized size for the vectors, you can ensure that all vectors of a
particular length represent the same magnitude on all the plots by setting both VHC and VLC to
negative values. If you do not actually want to remove any vectors from the plot, make VLC smaller
in absolute value than any expected magnitude. You can turn on Vectors statistics reporting using
the parameter VST in order to see if any vectors in the datasets are less the minimum magnitude
you have specified. See also the descriptions of parameters VFR, VRL, VHC, DMN, and VRM.
VMD - Vector Minimum Distance - Real
If VMD is set to a value greater than 0.0, it specifies, as a fraction of the viewport width, a
minimum distance between adjacent vectors arrows in the plot. The distribution of vectors is
analyzed and then vectors are selectively removed in order to ensure that the remaining vectors
are separated by at least the specified distance. The thinning algorithm requires that you supply
Vectors with a work array twice the size of the VVINIT arguments N and M multiplied together. Use
of this capability adds some processing time to the execution of Vectors. If VMD is set to a value
greater than 0.0 and no work array is provided, an error condition results.
If the data grid is transformed in such a way that adjacent grid cells become very close in NDC
space, as for instance in many map projections near the poles, you can use this parameter to
reduce the otherwise cluttered appearance of these regions of the plot. The default value of VMD
is 0.0.
VMN - Minimum Vector Magnitude - Real, Read-Only
After a call to VVINIT, VMN contains the value of the minimum vector magnitude in the U and V
vector component arrays. Later, after VVECTR is called, it is modified to contain the magnitude of
the smallest vector actually displayed in the plot. This is the vector with the smallest magnitude
greater than or equal to the value specified by VLC, the vector low cutoff parameter, (0.0 if VLC
has its default value) that falls within the user coordinate window boundaries. The value
contained in VMN is the same as that reported as the 'Minimum plotted vector magnitude' when
Vectors statistics reporting is enabled. It may be larger than the reference minimum magnitude
reported by the minimum vector text block if you specify the VLC parameter as a negative value.
VMN is initially set to a value of 0.0.
VMX - Maximum Vector Magnitude - Real, Read-Only
After a call to VVINIT, VMX contains the value of the maximum vector magnitude in the U and V
vector component arrays. Later, after VVECTR is called, it is modified to contain the magnitude of
the largest vector actually displayed in the plot. This is the vector with the largest magnitude
less than or equal to the value specified by VHC, the vector high cutoff parameter, (the largest
floating point value available on the machine if VHC has its default value, 0.0) that falls within
the user coordinate window boundaries. The value contained in VMX is the same as that reported as
the 'Maximum plotted vector magnitude' when Vectors statistics reporting is enabled. It may be
smaller than the reference maximum magnitude reported by the maximum vector text block if you
specify the VHC parameter as a negative value. VMX is initially set to a value of 0.0.
VPB - Viewport Bottom - Real
The parameter VPB has an effect only when SET is non-zero, specifying that Vectors should do the
call to SET. It specifies a minimum boundary value for the bottom edge of the viewport in NDC
space, and is constrained to a value between 0.0 and 1.0. It must be less than the value of the
Viewport Top parameter, VPT. The actual value of the viewport bottom edge used in the plot may be
greater than the value of VPB, depending on the setting of the Viewport Shape parameter, VPS. You
must initialize Vectors with a call to VVINIT after modifying this parameter. The default value of
VPB is 0.05.
VPL - Viewport Left - Real
The parameter VPL has an effect only when SET is non-zero, specifying that Vectors should do the
call to SET. It specifies a minimum boundary value for the left edge of the viewport in NDC space,
and is constrained to a value between 0.0 and 1.0. It must be less than the value of the Viewport
Right parameter, VPR. The actual value of the viewport left edge used in the plot may be greater
than the value of VPL, depending on the setting of the Viewport Shape parameter, VPS. You must
initialize Vectors with a call to VVINIT after modifying this parameter. The default value of VPL
is 0.05.
VPO - Vector Positioning Mode - Integer
VPO specifies the position of the vector arrow in relation to the grid point location of the
vector component data. Three settings are available, as follows:
Value Effect
<0 The head of the vector arrow is placed at the grid point location
0 (default) The center of the vector arrow is placed at the grid point location
>0 The tail of the vector arrow is placed at the grid point location
VPR - Viewport Right - Real
The parameter VPR has an effect only when SET is non-zero, specifying that Vectors should do the
call to SET. It specifies a maximum boundary value for the right edge of the viewport in NDC
space, and is constrained to a value between 0.0 and 1.0. It must be greater than the value of the
Viewport Left parameter, VPL. The actual value of the viewport right edge used in the plot may be
less than the value of VPR, depending on the setting of the Viewport Shape parameter, VPS. You
must initialize Vectors with a call to VVINIT after modifying this parameter. The default value of
VPR is 0.95.
VPS - Viewport Shape - Real
The parameter VPS has an effect only when SET is non-zero, specifying that Vectors should do the
call to SET; it specifies the desired viewport shape, as follows:
Value Effect
<0.0 The absolute value of VPS specifies the shape to use for the viewport., as the
ratio of the viewport width to its height,
0.0 The viewport completely fills the area defined by the boundaries specifiers, VPL,
VPR, VPB, VPT
>0.0,<1.0 (0.25, default)
Use R = (XCM-XC1)/(YCN-YC1) as the viewport shape if MIN(R, 1.0/R) is greater than
VPS. Otherwise determine the shape as when VPS is equal to 0.0.
>= 1.0 Use R = (XCM-XC1)/(YCN-YC1) as the viewport shape if MAX(R, 1.0/R) is less than
VPS. Otherwise make the viewport a square.
The viewport, whatever its final shape, is centered in, and made as large as possible in, the area
specified by the parameters VPB, VPL, VPR, and VPT. You must initialize Vectors with a call to
VVINIT after modifying this parameter. The default value of VPS is 25.
VPT - Viewport Top - Real
The parameter VPT has an effect only when SET is non-zero, specifying that Vectors should do the
call to SET. It specifies a maximum boundary value for the top edge of the viewport in NDC space,
and is constrained to a value between 0.0 and 1.0. It must be greater than the value of the
Viewport Bottom parameter, VPB. The actual value of the viewport top edge used in the plot may be
less than the value of VPT, depending on the setting of the Viewport Shape parameter, VPS. You
must initialize Vectors with a call to VVINIT after modifying this parameter. The default value of
VPT is 0.95.
VRL - Vector Reference Length - Real
Use this parameter to specify the realized length of the reference magnitude vector as a fraction
of the viewport width. Based on this value a reference length in NDC units is established, from
which the length of all vectors in the plot is derived. The relationship between magnitude and
length also depends on the setting of the minimum vector magnitude fraction parameter, VFR, but,
given the default value of VFR (0.0), the length of each vector is simply proportional to its
relative magnitude. Note that the arrow size parameters, AMN and AMX, allow independent control
over the minimum and maximum size of the vector arrowheads.
Given a reference length, Vectors calculates a maximum length based on the ratio of the reference
magnitude to the larger of the maximum magnitude in the data set and the reference magnitude
itself. This length is accessible in units of NDC via the read-only parameter, DMX. If VRL is set
less than or equal to 0.0, VVINIT calculates a default value for DMX, based on the size of a grid
box assuming a linear mapping from grid coordinates to NDC space. The value chosen is one half the
diagonal length of a grid box. By retrieving the value of DMX and calling GETSET to retrieve the
viewport boundaries after the call to VVINIT, you can make relative adjustments to the vector
length, as shown by the following example, where the maximum vector length is set to 1.5 times its
default value:
CALL VVINIT(...
CALL VVGETR(´DMX - NDC Maximum Vector Size´, DMX)
CALL GETSET(VL,VR,VB,VT,UL,UR,UB,UT,LL)
VRL = 1.5 * DMX / (VR - VL)
CALL VVSETR(´VRL - Vector Realized Length´, VRL)
CALL VVECTR(...
When VVECTR sees that VRL is greater than 0.0, it will calculate a new value for DMX. If VRL is
never set, the initially calculated value of DMX is used as the reference length. Do not rely on
the internal parameters used for setting the viewport, VPL, VPR, VPB and VPT to retrieve
information about viewport in lieu of using the GETSET call. These values are ignored entirely if
the SET parameter is zero, and even if used, the viewport may be adjusted from the specified
values depending on the setting of the viewport shape parameter, VPS. See also the descriptions of
VFR, VRM, and VHC. The default value of VRL is 0.0.
VRM - Vector Reference Magnitude - Real
The introduction of the parameter VRM means that it is now possible to specify an arbitrary vector
magnitude as the reference magnitude appearing in the "Maximum Vector Text Block" annotation. The
reference magnitude no longer needs to be greater or equal to the largest magnitude in the data
set. When VRM has a value greater than 0.0, it specifies the magnitude of the vector arrow drawn
at the reference length. See VRL for an explanation of how the reference length is determined. If
VRM is less than or equal to 0.0, the reference magnitude is determined by the value of VHC, the
vector high cutoff value. If, in turn, VHC is equal to 0.0 the maximum magnitude in the vector
field data set becomes the reference magnitude. The default value of VRM is 0.0.
VST - Vector Statistics Output Flag - Integer
If VST is set to one, VVECTR writes a summary of its operation to the default logical output unit,
including the number of vectors plotted, number of vectors rejected, minimum and maximum vector
magnitudes, and if coloring the vectors according to data in the scalar array, the maximum and
minimum scalar array values encountered. Here is a sample of the output:
VVECTR Statistics
Vectors plotted: 906
Vectors rejected by mapping routine: 0
Vectors under minimum magnitude: 121
Vectors over maximum magnitude: 0
Other zero length vectors: 0
Rejected special values: 62
Minimum plotted vector magnitude: 9.94109E-02
Maximum plotted vector magnitude: 1.96367
Minimum scalar value: -1.00000
Maximum scalar value: 1.00000
VSV - V Array Special Value - Real
VSV is the V vector component array special value. It is a value outside the range of the normal
data used to indicate that there is no valid data for this grid location. When SVF is set to 2 or
3, Vectors will not draw a vector whose V component has the special value. You must initialize
Vectors with a call to VVINIT after modifying this parameter. It has a default value of 1.0 E12.
WBA - Wind Barb Angle - Real
WBA sets the angle of the wind barb ticks in degrees as measured clockwise from the vector
direction. It also sets the angle between the hypotenuse of the triangle defining the pennant
polygon and the vector direction. You can render southern hemisphere wind barbs, which by
convention, have their ticks and pennants on the other side of the shaft, by setting WBA to a
negative value. WBA has an effect only when AST has the value 2.
WBC - Wind Barb Calm Circle Size - Real
WBC sets the diameter of the circle used to represent small vector magnitudes (less than 2.5) as a
fraction of the overall wind barb length (the value of the VRL parameter). WBC has an effect only
when AST has the value 2.
WBD - Wind Barb Distance Between Ticks - Real
WBD sets the distance between adjacent wind barbs ticks along the wind barb shaft as a fraction of
the overall wind barb length (the value of the VRL parameter). Half this distance is used as the
spacing between adjacent wind barb pennants. Note that there is nothing to to prevent ticks and/or
pennants from continuing off the end of the shaft if a vector of high enough magnitude is
encountered. You are responsible for adjusting the parameters appropriately for the range of
magnitudes you need to handle. WBD has an effect only when AST has the value 2.
WBS - Wind Barb Scale Factor - Real
WBS specifies a factor by which magnitudes passed to the wind barb drawing routines are to be
scaled. It can be used to convert vector data given in other units into the conventional units
used with wind barbs, which is knots. For instance, if the data are in meters per second, you
could set WBS to 1.8974 to create a plot with conventional knot-based wind barbs. Note that
setting WBS does not currently have any effect on the magnitude values written into the maximum or
minimum vector legends. WBS has an effect only when AST has the value 2.
WBT - Wind Barb Tick Size - Real
WBT the length of the wind barb ticks as a fraction of the overall length of a wind barb (the
value of the VRL parameter). The wind barb length is defined as the length of the wind barb shaft
plus the projection of a full wind barb tick along the axis of the shaft. Therefore, increasing
the value of WBT, for a given value of VRL has the effect of reducing the length of the shaft
itself somewhat. You may need to increase VRL itself to compensate. WBT also sets the hypotenuse
length of the triangle defining the pennant polygon. WBT has an effect only when AST has the value
2.
WDB - Window Bottom - Real
When VVINIT does the call to SET, the parameter WDB is used to determine argument number 7, the
user Y coordinate at the bottom of the window. If WDB is not equal to WDT, WDB is used. If WDB is
equal to WDT, but YC1 is not equal to YCN, then YC1 is used. Otherwise, the value 1.0 is used. You
must initialize Vectors with a call to VVINIT after modifying this parameter. The default value of
WDB is 0.0.
WDL - Window Left - Real
When VVINIT the call to SET, the parameter WDL is used to determine argument number 5, the user X
coordinate at the left edge of the window. If WDL is not equal to WDR, WDL is used. If WDL is
equal to WDR, but XC1 is not equal to XCM, then XC1 is used. Otherwise, the value 1.0 is used. You
must initialize Vectors with a call to VVINIT after modifying this parameter. The default value of
WDL is 0.0.
WDR - Window Right - Real
When VVINIT does the call to SET, the parameter WDR is used to determine argument number 6, the
user X coordinate at the right edge of the window. If WDR is not equal to WDL, WDR is used. If WDR
is equal to WDL, but XCM is not equal to XC1, then XCM is used. Otherwise, the value of the
VVINIT input parameter, M, converted to a real, is used. You must initialize Vectors with a call
to VVINIT after modifying this parameter. The default value of WDR is 0.0.
WDT - Window Top - Real
When VVINIT does the call to SET, the parameter WDB is used to determine argument number 8, the
user Y coordinate at the top of the window. If WDT is not equal to WDB, WDT is used. If WDT is
equal to WDB, but YCN is not equal to YC1 then YCN is used. Otherwise, the value of the VVINIT
input parameter, N, converted to a real, is used. You must initialize Vectors with a call to
VVINIT after modifying this parameter. The default value of WDT is 0.0.
XC1 - X Coordinate at Index 1 - Real
The parameter XC1 specifies the X coordinate value that corresponds to a value of 1 for the first
subscript of the U, V, vector component arrays as well as for the P scalar data array, if used.
Together with XCM, YC1, and YCN it establishes the mapping from grid coordinate space to data
coordinate space. If XC1 is equal to XCM, 1.0 will be used. You must initialize Vectors with a
call to VVINIT after modifying this parameter. The default value of XC1 is 0.0.
XCM - X Coordinate at Index M - Real
The parameter XCM specifies the X coordinate value that corresponds to the value of the VVINIT
input parameter, M, for the first subscript of the U and V vector component arrays as well as for
the P scalar data array, if used. Together with XC1, YC1, and YCN it establishes the mapping from
grid coordinate space to data coordinate space. If XC1 is equal to XCM, the value of M, converted
to a real, will be used. You must initialize Vectors with a call to VVINIT after modifying this
parameter. The default value of XCM is 0.0.
XIN - X Axis Array Increment (Grid) - Integer
XIN controls the step size through first dimensional subscripts of the U,V vector component arrays
and also through the P scalar data array if it is used. For dense arrays plotted at a small scale,
you could set this parameter to a value greater than one to reduce the crowding of the vectors and
hopefully improve the intelligibility of the plot. The grid point with subscripts (1,1) is always
included in the plot, so if XIN has a value of three, for example, only grid points with first
dimension subscripts 1, 4, 7... (and so on) will be plotted. See also YIN. You must initialize
Vectors with a call to VVINIT after modifying this parameter. The default value of XIN is 1.
YC1 - Y Coordinate at Index 1 - Real
The parameter YC1 specifies the Y coordinate value that corresponds to a value of 1 for the first
subscript of the U, V, vector component arrays as well as for the P scalar data array, if used.
Together with YCN, XC1, and XCM it establishes the mapping from grid coordinate space to data
coordinate space. If YC1 is equal to YCN, 1.0 will be used. You must initialize Vectors with a
call to VVINIT after modifying this parameter. The default value of YC1 is 0.0.
YCN - Y Coordinate at Index N - Real
The parameter YCN specifies the Y coordinate value that corresponds to the value of the VVINIT
input parameter, N, for the second subscript of the U and V vector component arrays as well as the
P scalar data array, if used. Together with YC1, XC1, and XCM it establishes the mapping from
grid coordinate space to data coordinate space. If YC1 is equal to YCN, the value of N, converted
to a real, will be used. You must initialize Vectors with a call to VVINIT after modifying this
parameter. The default value of YCN is 0.0.
YIN - Y Axis Array Increment (Grid) - Integer
YIN controls the step size through the second dimension subscripts of the U and V vector component
arrays and also through the P scalar data array if it is used. For dense arrays plotted at a small
scale, you could set this parameter to a value greater than one to reduce the crowding of the
vectors and hopefully improve the intelligibility of the plot. The grid point with subscripts
(1,1) is always included in the plot, so if YIN has a value of three, for example, only grid
points with second dimension subscripts 1, 4, 7... (and so on) will be plotted. See also XIN. You
must initialize Vectors with a call to VVINIT after modifying this parameter. The default value of
YIN is 1.
ZFC - Zero Field Text Block Color - Integer
If ZFC is greater or equal to zero, it specifies the GKS color index to use to color the Zero
Field text block. Otherwise the Zero Field text block is colored using the current GKS text color
index. The default value of ZFC is -1.
ZFP - Zero Field Text Block Positioning Mode - Integer
The ZFP parameter allows you to justify, using any of the 9 standard justification modes, the Zero
Field text block unit with respect to the position established by the parameters, ZFX and ZFY The
position modes are supported as follows:
Mode Justification
-4 The lower left corner of the text block is positioned at ZFX, ZFY.
-3 The center of the bottom edge is positioned at ZFX, ZFY.
-2 The lower right corner is positioned at ZFX, ZFY.
-1 The center of the left edge is positioned at ZFX, ZFY.
0 (default) The text block is centered along both axes at ZFX, ZFY.
1 The center of the right edge is positioned at ZFX, ZFY.
2 The top left corner is positioned at ZFX, ZFY.
3 The center of the top edge is positioned at ZFX, ZFY.
4 The top right corner is positioned at ZFX, ZFY.
ZFS - Zero Field Text Block Character Size - Real
ZFS specifies the size of the characters used in the Zero Field graphics text block as a fraction
of the viewport width. The default value is 0.033.
ZFT - Zero Field Text String - Character* 36
Use ZFT to modify the text of the Zero Field text block. The Zero Field text block may appear
whenever the U and V vector component arrays contain data such that all the grid points otherwise
eligible for plotting contain zero magnitude vectors. Currently the string length is limited to 36
characters. Set ZFT to a single space (´ ´) to prevent the text from being displayed. The default
value for the text is ´Zero Field´.
ZFX - Zero Field Text Block X Coordinate - Real
ZFX establishes the X coordinate of the Zero Field graphics text block as a fraction of the
viewport width. Values less than 0.0 or greater than 1.0 are permissible and respectively
represent regions to the left or right of the viewport. The actual position of the block relative
to ZFX depends on the value assigned to the Zero Field Positioning Mode parameter, ZFP. The
default value is 0.5.
ZFY - Zero Field Text Block Y Coordinate - Real
ZFY establishes the Y coordinate of the minimum vector graphics text block as a fraction of the
viewport height. Values less than 0.0 or greater than 1.0 are permissible and respectively
represent regions below and above the viewport. The actual position of the block relative to ZFY
depends on the value assigned to the Zero Field Positioning Mode parameter, ZFP. The default value
is 0.5.
SEE ALSO
Online: vectors, vvectr, vvgetc, vvgeti, vvgetr, vvinit, vvrset, vvsetc, vvseti, vvsetr. vvudmv, vvumxy,
ncarg_cbind.
Hardcopy: NCAR Graphics Fundamentals, UNIX Version
COPYRIGHT
Copyright (C) 1987-2009
University Corporation for Atmospheric Research
The use of this Software is governed by a License Agreement.
UNIX April 1993 Vectors_params(3NCARG)