COMPLEX FUNCTION CACOS(Z)
C***BEGIN PROLOGUE  CACOS
C***DATE WRITTEN   770401   (YYMMDD)
C***REVISION DATE  820801   (YYMMDD)
C***CATEGORY NO.  C4A
C***KEYWORDS  ARC COSINE,COMPLEX,ELEMEMTARY FUNCTION
C***AUTHOR  FULLERTON, W., (LANL)
C***PURPOSE  Computes the complex arc Cosine.
C***DESCRIPTION
C
C CACOS(Z) calculates the complex trigonometric arc cosine of Z.
C The result is in units of radians, and the real part is in the
C first or second quadrant.
C***REFERENCES  (NONE)
C***ROUTINES CALLED  CASIN
C***END PROLOGUE  CACOS