FUNCTION CHU(A,B,X)
C***BEGIN PROLOGUE  CHU
C***DATE WRITTEN   770801   (YYMMDD)
C***REVISION DATE  820801   (YYMMDD)
C***CATEGORY NO.  C11
C***KEYWORDS  CONFLUENT,HYPERGEOMETRIC,
C             LOGARITHM CONFLUENT HYPERGEOMETRIC FUNCTION,
C             SPECIAL FUNCTION
C***AUTHOR  FULLERTON, W., (LANL)
C***PURPOSE  Computes the logarithmic confluent hypergeometric function.
C***DESCRIPTION
C
C CHU computes the logarithmic confluent hypergeometric function,
C U(A,B,X).
C
C Input Parameters:
C       A   real
C       B   real
C       X   real and positive
C
C This routine is not valid when 1+A-B is close to zero if X is small.
C***REFERENCES  (NONE)
C***ROUTINES CALLED  EXPREL,GAMMA,GAMR,POCH,POCH1,R1MACH,R9CHU,XERROR
C***END PROLOGUE  CHU