# atanh.f

          FUNCTION ATANH (X)
    C***BEGIN PROLOGUE  ATANH
    C***PURPOSE  Compute the arc hyperbolic tangent.
    C***LIBRARY   SLATEC (FNLIB)
    C***CATEGORY  C4C
    C***TYPE      SINGLE PRECISION (ATANH-S, DATANH-D, CATANH-C)
    C***KEYWORDS  ARC HYPERBOLIC TANGENT, ATANH, ELEMENTARY FUNCTIONS,
    C             FNLIB, INVERSE HYPERBOLIC TANGENT
    C***AUTHOR  Fullerton, W., (LANL)
    C***DESCRIPTION
    C
    C ATANH(X) computes the arc hyperbolic tangent of X.
    C
    C Series for ATNH       on the interval  0.          to  2.50000D-01
    C                                        with weighted error   6.70E-18
    C                                         log weighted error  17.17
    C                               significant figures required  16.01
    C                                    decimal places required  17.76
    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  ATANH