/************************************************************************
 *                                                                      *
 *                              N O T I C E                             *
 *                                                                      *
 *                      Copyright Abandoned, 1987, Fred Fish            *
 *                                                                      *
 *      This previously copyrighted work has been placed into the       *
 *      public domain by the author (Fred Fish) and may be freely used  *
 *      for any purpose, private or commercial.  I would appreciate     *
 *      it, as a courtesy, if this notice is left in all copies and     *
 *      derivative works.  Thank you, and enjoy...                      *
 *                                                                      *
 *      The author makes no warranty of any kind with respect to this   *
 *      product and explicitly disclaims any implied warranties of      *
 *      merchantability or fitness for any particular purpose.          *
 *                                                                      *
 ************************************************************************
 */

/*
 *  FUNCTION
 *
 *      poly   double precision polynomial evaluation
 *
 *  KEY WORDS
 *
 *      poly
 *      machine independent routines
 *      math libraries
 *
 *  DESCRIPTION
 *
 *      Evaluates a polynomial and returns double precision
 *      result.  Is passed a the order of the polynomial,
 *      a pointer to an array of double precision polynomial
 *      coefficients (in ascending order), and the independent
 *      variable.
 *
 *  USAGE
 *
 *      double poly (order, coeffs, x)
 *      int order;
 *      double *coeffs;
 *      double x;
 *
 *  PROGRAMMER
 *
 *      Fred Fish
 *
 *  INTERNALS
 *
 *      Evalates the polynomial using recursion and the form:
 *
 *              P(x) = P0 + x(P1 + x(P2 +...x(Pn)))
 *
 */

#include <stdio.h>
#include "pml.h"

double poly (order, coeffs, x)
register int order;
double *coeffs;
double x;
{
    double curr_coeff;
    double rtn_value;

    DBUG_ENTER ("poly");
    DBUG_5 ("polyin", "args %d %#x %le", order, coeffs, x);
    if (order <= 0) {
        rtn_value = *coeffs;
    } else {
        curr_coeff = *coeffs;   /* Bug in Unisoft's compiler.  Does not */
        coeffs++;               /* generate good code for *coeffs++ */
        rtn_value = curr_coeff + x * poly (--order, coeffs, x);
    }
    DBUG_3 ("polyout", "result %le", rtn_value);
    DBUG_RETURN (rtn_value);
}