NAME

       gevtm - Evaluate a transform matrix and construct GKS segment

DESCRIPTION

       GEVTM  (Evaluate  transformation matrix) - Constructs a GKS segment transformation matrix starting from a
       given point, a shift vector, a rotation angle, and X and Y scale factors.

SYNOPSIS

       CALL GEVTM(X0,Y0,DX,DY,PHI,FX,FY,SW,MOUT)

C-BINDING SYNOPSIS

       #include <ncarg/gks.h>

       void geval_tran_matrix(const Gpoint  *point,  const  Gvec  *shift,  Gdouble  angle,  const  Gvec  *scale,
       Gcoord_switch coord_switch, Gtran_matrix tran_matrix);

DESCRIPTION

       X0          (Real,  Input)  -  An  X  coordinate  value  for a fixed point to be used for the scaling and
                   rotation parts of the output transformation.  X is either in world coordinates or  normalized
                   device coordinates depending on the setting of the argument SW described below.

       Y0          (Real,  Input)  -  A  Y  coordinate  value  for  a fixed point to be used for the scaling and
                   rotation parts of the output transformation.  Y is either in world coordinates or  normalized
                   device coordinates depending on the setting of the argument SW described below.

       DX          (Real,  Input)  -  The  X  component of a shift vector to be used for the scaling part of the
                   output transformation.  DX is either in world coordinates or  normalized  device  coordinates
                   depending on the setting of the argument SW described below.

       DY          (Real,  Input)  -  The  Y  component of a shift vector to be used for the scaling part of the
                   output transformation.  DY is either in world coordinates or  normalized  device  coordinates
                   depending on the setting of the argument SW described below.

       PHI         (Real,  Input)  -  The  rotation  angle,  in radians, to be used for the rotation part of the
                   output transformation.

       FX          (Real, Input) - An X coordinate scale factor to be used in the scaling  part  of  the  output
                   transformation.

       FY          (Real,  Input)  -  A  Y  coordinate scale factor to be used in the scaling part of the output
                   transformation.

       SW          (Integer, Input) - A coordinate switch to indicate whether the values for the  arguments  X0,
                   Y0,  DX,  and DY (described above) are in world coordinates or normalized device coordinates.
                   SW=0 indicates world coordinates and SW=1 indicates normalized device coordinates.

       MOUT        (Real, Output) - A 2x3 array that contains the GKS transformation matrix in a form  that  can
                   be used as input to other GKS functions such as GSSGT.

USAGE

       If  world  coordinates  are  used,  the  shift  vector and the fixed point are transformed by the current
       normalization transformation.

       The order of the transformation operations as built into the output matrix is:  scale  (relative  to  the
       fixed point); rotate (relative to the fixed point; shift.

       Elements  MOUT(1,3) and MOUT(2,3) are in normalized device coordinates and the other elements of MOUT are
       unitless.

EXAMPLE

       The following code

             PI = 3.1415926
             CALL GEVTM(.5,.5,.25,0.,45.*PI/180.,.5,1.5,0,TM)

       would produce a transformation matrix in TM that would: scale the  X  coordinates  by  .5,  scale  the  Y
       coordinates by 1.5 (relative to the fixed point of (.5,.5) ); rotate by 45 degrees (relative to the fixed
       point  (.5,.5)  );  and  shift  by  .25 in X and 0. in Y.  The input values for the fixed point and shift
       vector are in world coordintes.

ACCESS

       To use GKS routines, load the NCAR GKS-0A library ncarg_gks.

SEE ALSO

       Online: gactm, gclsg, gcrsg, gcsgwk, gdsg, gqopsg, gqsgus, gssgt., geval_tran_matrix

       Hardcopy: "User's Guide for NCAR GKS-0A Graphics"

COPYRIGHT

       Copyright (C) 1987-2009
       University Corporation for Atmospheric Research
       The use of this Software is governed by a License Agreement.

UNIX                                               March 1993                                      GEVTM(3NCARG)