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
vx, vy = NumRu::DCL.stftrn(ux,uy)
ux, uy = NumRu::DCL.stitrn(vx,vy)
NumRu::DCL.ststrn(itr,cxa,cya,vxoff,vyoff)

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
    .