catan2.f
COMPLEX FUNCTION CATAN2 (CSN, CCS)
C***BEGIN PROLOGUE CATAN2
C***PURPOSE Compute the complex arc tangent in the proper quadrant.
C***LIBRARY SLATEC (FNLIB)
C***CATEGORY C4A
C***TYPE COMPLEX (CATAN2-C)
C***KEYWORDS ARC TANGENT, ELEMENTARY FUNCTIONS, FNLIB, POLAR ANGEL,
C QUADRANT, TRIGONOMETRIC
C***AUTHOR Fullerton, W., (LANL)
C***DESCRIPTION
C
C CATAN2(CSN,CCS) calculates the complex trigonometric arc
C tangent of the ratio CSN/CCS and returns a result whose real
C part is in the correct quadrant (within a multiple of 2*PI). The
C result is in units of radians and the real part is between -PI
C and +PI.
C
C***REFERENCES (NONE)
C***ROUTINES CALLED CATAN, XERMSG
C***REVISION HISTORY (YYMMDD)
C 770401 DATE WRITTEN
C 890531 Changed all specific intrinsics to generic. (WRB)
C 890531 REVISION DATE from Version 3.2
C 891214 Prologue converted to Version 4.0 format. (BAB)
C 900315 CALLs to XERROR changed to CALLs to XERMSG. (THJ)
C 900326 Removed duplicate information from DESCRIPTION section.
C (WRB)
C***END PROLOGUE CATAN2