exprel.f
FUNCTION EXPREL (X)
C***BEGIN PROLOGUE EXPREL
C***PURPOSE Calculate the relative error exponential (EXP(X)-1)/X.
C***LIBRARY SLATEC (FNLIB)
C***CATEGORY C4B
C***TYPE SINGLE PRECISION (EXPREL-S, DEXPRL-D, CEXPRL-C)
C***KEYWORDS ELEMENTARY FUNCTIONS, EXPONENTIAL, FIRST ORDER, FNLIB
C***AUTHOR Fullerton, W., (LANL)
C***DESCRIPTION
C
C Evaluate EXPREL(X) = (EXP(X) - 1.0) / X. For small ABS(X) the
C Taylor series is used. If X is negative, the reflection formula
C EXPREL(X) = EXP(X) * EXPREL(ABS(X))
C may be used. This reflection formula will be of use when the
C evaluation for small ABS(X) is done by Chebyshev series rather than
C Taylor series. EXPREL and X are single precision.
C
C***REFERENCES (NONE)
C***ROUTINES CALLED R1MACH
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***END PROLOGUE EXPREL