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Procedure
Abstract
Required_Reading
Keywords
Declarations
Brief_I/O
Detailed_Input
Detailed_Output
Parameters
Exceptions
Files
Particulars
Examples
Restrictions
Literature_References
Author_and_Institution
Version

Procedure

  DACOSH ( Double precision arc hyperbolic cosine )
 
      DOUBLE PRECISION FUNCTION  DACOSH ( X )
 

Abstract

      Return the inverse hyperbolic cosine of a double
      precision argument.

Required_Reading

     None.

Keywords

      HYPERBOLIC,  MATH

Declarations

 
      DOUBLE PRECISION   X
 

Brief_I/O

      VARIABLE  I/O  DESCRIPTION
      --------  ---  --------------------------------------------------
       X         I   Number whose inverse hyperbolic cosine is desired.
                     X must be >= 1.

Detailed_Input

      X      is any double precision number greater than or equal to 1.

Detailed_Output

      DACOSH is the inverse hyperbolic cosine of X.

Parameters

     None.

Exceptions

      1) If X is less than 1.0d0, the error SPICE(INVALIDARGUMENT) is
         signalled.

Files

      None.

Particulars

      This function simply implements the definition of the inverse
      hyperbolic cosine as follows:

      DACOSH = DLOG (X + DSQRT (X*X-1.D0))

      If the input value is not valid, an error is signalled.

Examples

      The following table gives a few values for X and the resulting
      value of DACOSH.

      X                       DACOSH(X)
      ----------------------------------------------
      1.000000000000000      0.0000000000000000E+00
      10.00000000000000       2.993222846126381
      100.0000000000000       5.298292365610485
      1000.000000000000       7.600902209541989

Restrictions

      The value of the input variable X must be greater than or equal
      to 1.0d0.

Literature_References

      Any good book of mathematical tables and formulae, for example
      the "Standard Mathematical Tables" published by the Chemical
      Rubber Company.

Author_and_Institution

      H.A. Neilan     (JPL)
      W.M. Owen       (JPL)

Version

     SPICELIB Version 1.1.0, 17-MAY-1994 (HAN)

        Set the default function value to either 0, 0.0D0, .FALSE.,
        or blank depending on the type of the function.

     SPICELIB Version 1.0.1, 10-MAR-1992 (WLT)

        Comment section for permuted index source lines was added
        following the header.

     SPICELIB Version 1.0.0, 31-JAN-1990 (WMO)
Wed Apr  5 17:46:12 2017