6.4.1 STFTRN/STITRN/STSTRN

1.
Function
Performs a normalization transformation (transformation of UC and VC) or map projection (transformation of TC and VC).

2.
Call
CALL STFTRN(UX,UY,VX,VY)
CALL STITRN(VX,VY,UX,UY)
CALL STSTRN(ITR,CXA,CYA,VX0,VY0)

3.
Explanation of Arguments
UX,UY (R) The coordinates of UC/TC
VX,VY (R) The coordinates of VC.
ITR (I) Transformation function number
CXA,CYA (R) Factor to multiply coordinate value by
VX0,VY0 (R) The position of the origin in VC

4.
Notes
(a)
In a map projection, if transformation is impossible due to factors such as singular points, the value of the internal variable RUNDEF managed by GLpGET/GLpSET is returned. (The initial value is -999.0.)
(b)
This function performs the following operations.
  • Performs a basic transformation on (UX,UY)  to (XX,YY) according to the transformation function number
  • Furthermore, it expands or shifts by 
    VX = CXA*XX + VX0
    VY = CYA*XX + VY0
    .