d9chu.f
DOUBLE PRECISION FUNCTION D9CHU (A, B, Z)
C***BEGIN PROLOGUE D9CHU
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Warning: this routine is not intended to be user-callable.
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C***SUBSIDIARY
C***PURPOSE Evaluate for large Z Z**A * U(A,B,Z) where U is the
C logarithmic confluent hypergeometric function.
C***LIBRARY SLATEC (FNLIB)
C***CATEGORY C11
C***TYPE DOUBLE PRECISION (R9CHU-S, D9CHU-D)
C***KEYWORDS FNLIB, LOGARITHMIC CONFLUENT HYPERGEOMETRIC FUNCTION,
C SPECIAL FUNCTIONS
C***AUTHOR Fullerton, W., (LANL)
C***DESCRIPTION
C
C Evaluate for large Z Z**A * U(A,B,Z) where U is the logarithmic
C confluent hypergeometric function. A rational approximation due to Y.
C L. Luke is used. When U is not in the asymptotic region, i.e., when A
C or B is large compared with Z, considerable significance loss occurs.
C A warning is provided when the computed result is less than half
C precision.
C
C***REFERENCES (NONE)
C***ROUTINES CALLED D1MACH, 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 900720 Routine changed from user-callable to subsidiary. (WRB)
C***END PROLOGUE D9CHU