/* dcbrt.f -- translated by f2c (version 19980913).
   You must link the resulting object file with the libraries:
	-lf2c -lm   (in that order)
*/

#include "f2c.h"

/* Table of constant values */

static doublereal c_b2 = .33333333333333331;

/* $Procedure  DCBRT ( Double precision cube root ) */
doublereal dcbrt_(doublereal *x)
{
    /* System generated locals */
    doublereal ret_val, d__1, d__2;

    /* Builtin functions */
    double pow_dd(doublereal *, doublereal *), d_sign(doublereal *, 
	    doublereal *);

/* $ Abstract */

/*      Return the cube root of a double precision number. */

/* $ Copyright */

/*     Copyright (1995), California Institute of Technology. */
/*     U.S. Government sponsorship acknowledged. */

/* $ Required_Reading */

/*     None. */

/* $ Keywords */

/*      MATH,  ROOT */

/* $ Declarations */
/* $ 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. */

/* $ 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 */

/* $ Exceptions */

/*      Error free. */

/* $ Files */

/*      None */

/* $ Author_and_Institution */

/*      W.M. Owen       (JPL) */

/* $ Literature_References */

/*      None */

/* $ 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) */

/* -& */
/* $ Index_Entries */

/*     d.p. cube root */

/* -& */

    d__2 = abs(*x);
    d__1 = pow_dd(&d__2, &c_b2);
    ret_val = d_sign(&d__1, x);

    return ret_val;
} /* dcbrt_ */