2 C.----------------------------------------------------------------------
4 C. PHOTOS: PHOton radiation in decays calculation of ANgle '2'
6 C. Purpose: Calculate angle from X and Y
8 C. Input Parameters: X, Y
10 C. Output Parameter: Function value
12 C. Author(s): S. Jadach Created at: 01/01/89
13 C. B. van Eijk Last Update: 02/01/90
15 C.----------------------------------------------------------------------
17 DOUBLE PRECISION PHOAN2
20 COMMON/PHPICO/PI,TWOPI
21 IF (ABS(Y).LT.ABS(X)) THEN
23 IF (X.LE.0.D0) PHOAN2=PI-PHOAN2
25 PHOAN2=ACOS(X/SQRT(X**2+Y**2))