# dchu.f

          DOUBLE PRECISION FUNCTION DCHU (A, B, X)
    C***BEGIN PROLOGUE  DCHU
    C***PURPOSE  Compute the logarithmic confluent hypergeometric function.
    C***LIBRARY   SLATEC (FNLIB)
    C***CATEGORY  C11
    C***TYPE      DOUBLE PRECISION (CHU-S, DCHU-D)
    C***KEYWORDS  FNLIB, LOGARITHMIC CONFLUENT HYPERGEOMETRIC FUNCTION,
    C             SPECIAL FUNCTIONS
    C***AUTHOR  Fullerton, W., (LANL)
    C***DESCRIPTION
    C
    C DCHU(A,B,X) calculates the double precision logarithmic confluent
    C hypergeometric function U(A,B,X) for double precision arguments
    C A, B, and X.
    C
    C This routine is not valid when 1+A-B is close to zero if X is small.
    C
    C***REFERENCES  (NONE)
    C***ROUTINES CALLED  D1MACH, D9CHU, DEXPRL, DGAMMA, DGAMR, DPOCH,
    C                    DPOCH1, XERMSG
    C***REVISION HISTORY  (YYMMDD)
    C   770801  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  DCHU