DPSI(3)

SYNOPSIS
DOUBLE PRECISION FUNCTION DPSI (X)

NAME
dpsi - Compute the Psi (or Digamma) function.

LIBRARY
SLATEC (FNLIB)

CATEGORY
C7C

TYPE
DOUBLE PRECISION (PSI-S, DPSI-D, CPSI-C)

KEYWORDS
DIGAMMA FUNCTION, FNLIB, PSI FUNCTION, SPECIAL FUNCTIONS

AUTHOR
Fullerton, W., (LANL)

DESCRIPTION
DPSI calculates the double precision Psi (or Digamma) function for double precision argument X. PSI(X) is the logarithmic derivative of the Gamma function of X. Series for PSI on the interval 0. to 1.00000E+00 with weighted error 5.79E-32 log weighted error 31.24 significant figures required 30.93 decimal places required 32.05 Series for APSI on the interval 0. to 1.00000E-02 with weighted error 7.75E-33 log weighted error 32.11 significant figures required 28.88 decimal places required 32.71

REFERENCES
(NONE)

ROUTINES CALLED
D1MACH, DCOT, DCSEVL, INITDS, XERMSG

REVISION HISTORY (YYMMDD)
770601 DATE WRITTEN
890531 Changed all specific intrinsics to generic. (WRB)
890911 Removed unnecessary intrinsics. (WRB)
890911 REVISION DATE from Version 3.2
891214 Prologue converted to Version 4.0 format. (BAB)
900315 CALLs to XERROR changed to CALLs to XERMSG. (THJ)
900727 Added EXTERNAL statement. (WRB)
920618 Removed space from variable name. (RWC, WRB)