# 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