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DCL:GRPH1:STPACK: Transformation Functions:Explanation of Subroutines: Coordinate Transformation

6.3.1 STFTRF/STITRF/STSTRF/STQTRF

1.

Function

Performs a normalization transformation (transformation of UC and VC)

2.

Call

CALL STFTRF(UX,UY,VX,VY)
CALL STITRF(VX,VY,UX,UY)
CALL STSTRF(LMAP)
CALL STQTRF(LMAP)

3.

Explanation of Arguments

UX,UY	(R)	Coordinates in UC.
VX,VY	(R)	Coordinates in VC.
LMAP	(L)	A flag indicating a map projection function

4.

Notes

(a)

These functions internally call STFRAD, STFROT, and STFTRN.

(b)

When LFLAG=.TRUE., STFTRN is called after coordinate rotation by STFROT.

(c)

In map projections, when transformation is not possible due to such factors as a singular point, the value of the internal variable RUNDEF handled by GLpGET/GLpSET is returned. (The initial value is -999.0.)