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.