SLATEC Routines --- DATANH ---

*DECK DATANH
      DOUBLE PRECISION FUNCTION DATANH (X)
C***BEGIN PROLOGUE  DATANH
C***PURPOSE  Compute the arc hyperbolic tangent.
C***LIBRARY   SLATEC (FNLIB)
C***CATEGORY  C4C
C***TYPE      DOUBLE 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 DATANH(X) calculates the double precision arc hyperbolic
C tangent for double precision argument X.
C
C Series for ATNH       on the interval  0.          to  2.50000E-01
C                                        with weighted error   6.86E-32
C                                         log weighted error  31.16
C                               significant figures required  30.00
C                                    decimal places required  31.88
C
C***REFERENCES  (NONE)
C***ROUTINES CALLED  D1MACH, DCSEVL, INITDS, XERMSG
C***REVISION HISTORY  (YYMMDD)
C   770601  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***END PROLOGUE  DATANH