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ACS ASN ATN COS SIN TAN PI
Name
ATN
Syntax
ATN(expression)
Aufklappen Range
expression, Type real
Aufklappen Description
Returns the angle in the right angled triangle, which opposite to the adjacent are in proportion expression:1.

This funcion is inverse to the tangent function TAN.
Aufklappen Example
s = y/x   ! = gradient
angle = ATN(s)
Aufklappen Tips and Tricks
The arc tangent offers not for all quadrants the correct angle related to the X-axis directly. One as to differ by the gradient (x/y) in the following cases:

IF x=0 AND y=0 THEN
  angle=0
  ELSE
  IF x THEN angle=ATN(y/x) ELSE angle=90+180*(y<0)
  IF angle<0 AND x<0 and y>0 THEN angle=180+angle
  IF angle>0 AND x<0 and y<0 THEN angle=180+angle
  IF angle<0 AND x>0 and y<0 THEN angle=angle+360
  IF angle>=360 THEN angle=angle-360
  ENDIF


The same functionality in a compact code:

IF x THEN
  angle=360*FRA((360+ATN(y/x)+(x<0)*180)/360)
  ELSE
  angle=90+180*(y<0)
  ENDIF
Aufklappen References
GDL-Handbuch 4.5 (DE) p. 95
GDL-Handbuch 5.0 (DE) p. 126
GDL-Handbuch 6.0 (DE) p. 175
GDL-Handbuch 6.5 (DE) p. 177
GDL-Handbuch 7.0 (DE) p. 177
GDL-Handbuch 8.0 (DE) p. 120
GDL-Handbuch 8.1 (DE) p. 121
GDL-Handbuch 9.0 (DE) p. 200
GDL-Handbuch 10.0 (DE) p. 202
GDL-Handbuch 11.0 (DE) p. 208
GDL Reference Guide 9.0 (INT) p. 194
GDL Reference Guide 10.0 (INT) p. 200
GDL Reference Guide 11.0 (INT) p. 200
 





Abb. 1: Gradient at the unit circle


Abb. 2: The gradient rectangle.