*DECK CACOSH
      COMPLEX FUNCTION CACOSH (Z)
C***BEGIN PROLOGUE  CACOSH
C***PURPOSE  Compute the arc hyperbolic cosine.
C***LIBRARY   SLATEC (FNLIB)
C***CATEGORY  C4C
C***TYPE      COMPLEX (ACOSH-S, DACOSH-D, CACOSH-C)
C***KEYWORDS  ACOSH, ARC HYPERBOLIC COSINE, ELEMENTARY FUNCTIONS, FNLIB,
C             INVERSE HYPERBOLIC COSINE
C***AUTHOR  Fullerton, W., (LANL)
C***DESCRIPTION
C
C CACOSH(Z) calculates the complex arc hyperbolic cosine of Z.
C
C***REFERENCES  (NONE)
C***ROUTINES CALLED  CACOS
C***REVISION HISTORY  (YYMMDD)
C   770401  DATE WRITTEN
C   861211  REVISION DATE from Version 3.2
C   891214  Prologue converted to Version 4.0 format.  (BAB)
C***END PROLOGUE  CACOSH
      COMPLEX Z, CI, CACOS
      SAVE CI
      DATA CI /(0.,1.)/
C***FIRST EXECUTABLE STATEMENT  CACOSH
      CACOSH = CI*CACOS(Z)
C
      RETURN
      END