SLATEC Routines --- CPSI ---

*DECK CPSI
      COMPLEX FUNCTION CPSI (ZIN)
C***BEGIN PROLOGUE  CPSI
C***PURPOSE  Compute the Psi (or Digamma) function.
C***LIBRARY   SLATEC (FNLIB)
C***CATEGORY  C7C
C***TYPE      COMPLEX (PSI-S, DPSI-D, CPSI-C)
C***KEYWORDS  DIGAMMA FUNCTION, FNLIB, PSI FUNCTION, SPECIAL FUNCTIONS
C***AUTHOR  Fullerton, W., (LANL)
C***DESCRIPTION
C
C PSI(X) calculates the psi (or digamma) function of X.  PSI(X)
C is the logarithmic derivative of the gamma function of X.
C
C***REFERENCES  (NONE)
C***ROUTINES CALLED  CCOT, R1MACH, XERMSG
C***REVISION HISTORY  (YYMMDD)
C   780501  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   900727  Added EXTERNAL statement.  (WRB)
C***END PROLOGUE  CPSI