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/*************************************************************************
* Copyright (C) 2009-2010 Tavian Barnes <tavianator@gmail.com> *
* *
* This file is part of The Dimension Library. *
* *
* The Dimension Library is free software; you can redistribute it and/ *
* or modify it under the terms of the GNU Lesser General Public License *
* as published by the Free Software Foundation; either version 3 of the *
* License, or (at your option) any later version. *
* *
* The Dimension Library is distributed in the hope that it will be *
* useful, but WITHOUT ANY WARRANTY; without even the implied warranty *
* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU *
* Lesser General Public License for more details. *
* *
* You should have received a copy of the GNU Lesser General Public *
* License along with this program. If not, see *
* <http://www.gnu.org/licenses/>. *
*************************************************************************/
/*
* Utility functions for working with and numerically solving polynomials.
* Polynomials are represented as simple arrays where the ith element is the
* coefficient on x^i. In general, we are only interested in positive roots.
*/
#ifndef DIMENSION_POLYNOMIAL_H
#define DIMENSION_POLYNOMIAL_H
#include <stddef.h>
#include <stdio.h>
DMNSN_INLINE double
dmnsn_evaluate_polynomial(const double poly[], size_t degree, double x)
{
double ret = poly[degree];
ssize_t i;
for (i = degree - 1; i >= 0; --i) {
ret = ret*x + poly[i];
}
return ret;
}
DMNSN_INLINE double
dmnsn_evaluate_polynomial_derivative(const double poly[], size_t degree,
double x)
{
double ret = poly[degree]*degree;
size_t i;
for (i = degree - 1; i >= 1; --i) {
ret = ret*x + poly[i]*i;
}
return ret;
}
/* Stores the positive roots of poly[] in x[], and returns the number of such
roots that were stored */
size_t dmnsn_solve_polynomial(const double poly[], size_t degree, double x[]);
/* Helper function to print a polynomial */
void dmnsn_print_polynomial(FILE *file, const double poly[], size_t degree);
#endif /* DIMENSION_POLYNOMIAL_H */
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