Procedure

  DCBRT ( Double precision cube root )
 
      DOUBLE PRECISION FUNCTION  DCBRT ( X )
 

Abstract

      Return the cube root of a double precision number.

Required_Reading

     None.

Keywords

      MATH,  ROOT

Declarations

 
      DOUBLE PRECISION   X
 

Brief_I/O

      VARIABLE  I/O  DESCRIPTION
      --------  ---  --------------------------------------------------
       X         I     Number whose cube root is desired.

Detailed_Input

      X   may be any double precision value.

Detailed_Output

      DCBRT   is the cube root of the input value.

Parameters

     None.

Exceptions

      Error free.

Files

      None

Particulars

      DCBRT calculates the cube root of the input value by using the
      exponentiation operator to raise the input value to the 1/3
      power.  This operation, however, is performed on the absolute
      value of the input variable, and then the sign of the input
      is transferred to the output value.

      All values of the input variable X should be acceptible to the
      DCBRT.

Examples

      The following table gives sample values of the variable X and
      DCBRT(X)

       X                        DCBRT(X)
      --------------------------------------------------------------
       0.0D0                    0.0D0
       8.0D0                    2.0D0
      -1.0D3                   -1.0D1

Restrictions

      None

Literature_References

      None

Author_and_Institution

      W.M. Owen       (JPL)

Version

     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)