Provided by: libncarg-dev_6.6.2.dfsg.1-10build2_amd64 
NAME
VVINIT - Performs initialization tasks required before VVECTR may be called to plot a vector field,
including copying array size information into internal common block variables, establishing coordinate
system mappings and boundaries, determining the maximum and minimum vector magnitudes and scalar array
values, and, if required, setting up the color threshold value array.
SYNOPSIS
CALL VVINIT (U,LU,V,LV,P,LP,M,N,WRK,LW)
C-BINDING SYNOPSIS
#include <ncarg/ncargC.h>
void c_vvinit(float *u, int lu, float *v, int lv,
float *p, int lp, int m, int n,
float *wrk, int lw)
DESCRIPTION
U (REAL 2-dimensional array, dimensioned LU x n: n >= N, input): By default, assumed to contain
the first dimensional Cartesian components of the vector field. However, if PLR is non-zero,
it is treated as containing the vector magnitudes.
LU (INTEGER, input): Actual value of the first dimension of array U.
V (REAL 2-dimensional array, dimensioned LV x n: n >= N, input): By default, assumed to contain
the second dimensional Cartesian components of the vector field. However, if PLR is non-
zero, it is treated as containing the vector angles.
LV (INTEGER, input): Actual value of the first dimension of array V
P (REAL 2-dimensional array, dimensioned LP x n: n >= N, input): Array of scalar data that may
be used to color the vectors. The grid points are assumed to coincide with the grid points of
the U and V arrays. Required only if CTV has an absolute value of 2; otherwise this argument
is ignored and may be assigned a dummy value.
LP (INTEGER, input): Actual value of the first dimension of array P
M (INTEGER, input): Number of contiguous elements along the first dimensional axis containing
data to be processed in each of the arrays, U, V, and P (if used).
N (INTEGER, input): Number of contiguous elements along the second dimensional axis containing
data to be processed in each of the arrays, U, V, and P (if used).
WRK (REAL, array dimensioned n: n >= LW, input/output): Work array required only if the parameter
VMD is set to a value greater than 0.0. If required must be dimensioned greater or equal to 2
* M * N. Otherwise may be set to a dummy value.
LW (INTEGER, input): Assumed size of the array WRK. If the parameter VMD is set to a value
greater than 0.0, must be set to a value less than or equal to the dimension of the WRK
array, but greater or equal to 2 * M * N. Otherwise, this argument should be assigned the
integer value 0.
C-BINDING DESCRIPTION
The C-binding argument descriptions are the same as the FORTRAN argument descriptions with the following
exceptions:
lu The second dimension of u in the calling program.
lv The second dimension of v in the calling program.
lp The second dimension of p in the calling program.
m Number of contiguous elements along the second dimensional axis containing data to be
processed in each of the arrays, u, v, and p (if used).
n Number of contiguous elements along the first dimensional axis containing data to be
processed in each of the arrays, u, v, and p (if used).
USAGE
Call VVINIT before the first invocation of VVECTR and again anytime you modify the contents of the input
data arrays. You may precede a VVINIT call with any number of calls to the Vectors parameter setting
routines (VVSETC, VVSETI, or VVSETR). After the VVINIT call, you may still change certain parameters
before calling VVECTR. (Consult the vectors_params man page for further information on this point.)
Set up the two vector component arrays prior to calling VVINIT. To permit multiple purpose use of the
array space, the VVINIT argument list includes both the actual size and an assumed size for the first
dimension of each input array. Due to FORTRAN array ordering conventions, only the assumed size needs to
be specified for the second dimension. (Note: when using the C bindings, mentally exchange all
references to first and second dimensions in this discussion.) The arguments LU, LV, and LP contain the
actual size of the first dimensions of arrays U, V, and P respectively. Since the grid locations for each
of the data arrays are assumed to coincide, a single argument, M, represents the assumed size of the
first dimension for all the arrays. Similarly, the argument, N, is the assumed size of the second
dimension. The only requirement for the actual second dimension size is that it be greater than or equal
to N for each array.
The array specified by the WRK argument and its associated size specifier, LW, are used only when the
parameter VMD (Vector Minimum Distance) is given a value greater than 0.0. In this case, Vectors uses the
array to keep track of the location of each vector in NDC space so that the distances between vectors can
be compared. Based on these comparisons, Vectors eliminates some vectors such that the remaining vectors
are separated by at least the specified distance. If VMD is less than or equal to 0.0, you may assign an
arbitrary dummy value to WRK, but you should set LW to the integer value 0.
C-BINDING USAGE
C-Binding usage is the same as FORTRAN usage discussed above if the references to "first dimension" and
"second dimension" are exchanged.
EXAMPLES
Use the ncargex command to see the following relevant examples: bnchmk, fcover, ffex00, ffex01, ffex02,
ffex05, stex02, stex03, vvex01, vvex02.
ACCESS
To use VVINIT or c_vvinit, load the NCAR Graphics libraries ncarg, ncarg_gks, and ncarg_c, preferably in
that order.
MESSAGES
See the vectors man page for a description of all Vectors error messages and/or informational messages.
SEE ALSO
Online: vectors, vectors_params, vvectr, vvgetc, vvgeti, vvgetr, 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 VVINIT(3NCARG)