alnrel.f
FUNCTION ALNREL (X)
C***BEGIN PROLOGUE ALNREL
C***PURPOSE Evaluate ln(1+X) accurate in the sense of relative error.
C***LIBRARY SLATEC (FNLIB)
C***CATEGORY C4B
C***TYPE SINGLE PRECISION (ALNREL-S, DLNREL-D, CLNREL-C)
C***KEYWORDS ELEMENTARY FUNCTIONS, FNLIB, LOGARITHM
C***AUTHOR Fullerton, W., (LANL)
C***DESCRIPTION
C
C ALNREL(X) evaluates ln(1+X) accurately in the sense of relative
C error when X is very small. This routine must be used to
C maintain relative error accuracy whenever X is small and
C accurately known.
C
C Series for ALNR on the interval -3.75000D-01 to 3.75000D-01
C with weighted error 1.93E-17
C log weighted error 16.72
C significant figures required 16.44
C decimal places required 17.40
C
C***REFERENCES (NONE)
C***ROUTINES CALLED CSEVL, INITS, R1MACH, XERMSG
C***REVISION HISTORY (YYMMDD)
C 770401 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 900326 Removed duplicate information from DESCRIPTION section.
C (WRB)
C***END PROLOGUE ALNREL