diff options
Diffstat (limited to 'libdimension/dimension/polynomial.h')
| -rw-r--r-- | libdimension/dimension/polynomial.h | 35 |
1 files changed, 31 insertions, 4 deletions
diff --git a/libdimension/dimension/polynomial.h b/libdimension/dimension/polynomial.h index 56e3ac0..b0a9357 100644 --- a/libdimension/dimension/polynomial.h +++ b/libdimension/dimension/polynomial.h @@ -18,7 +18,8 @@ * <http://www.gnu.org/licenses/>. * *************************************************************************/ -/* +/** + * @file * 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. @@ -30,6 +31,14 @@ #include <stddef.h> #include <stdio.h> +/** + * Evaluate a polynomial at \p x. + * @param[in] poly The coefficients of the polynomial to evaluate, in order + * from lowest degree to highest degree. The array should + * have dimension <tt>degree + 1</tt>. + * @param[in] degree The degree of the polynomial. + * @param[in] x The value of the variable at which to evaluate. + */ DMNSN_INLINE double dmnsn_evaluate_polynomial(const double poly[], size_t degree, double x) { @@ -41,6 +50,12 @@ dmnsn_evaluate_polynomial(const double poly[], size_t degree, double x) return ret; } +/** + * Evaluate the derivative of a polynomial at \p x. + * @param[in] poly The coefficients of the polynomial to evaluate. + * @param[in] degree The degree of the polynomial. + * @param[in] x The value of the variable at which to evaluate. + */ DMNSN_INLINE double dmnsn_evaluate_polynomial_derivative(const double poly[], size_t degree, double x) @@ -53,11 +68,23 @@ dmnsn_evaluate_polynomial_derivative(const double poly[], size_t degree, return ret; } -/* Stores the positive roots of poly[] in x[], and returns the number of such - roots that were stored */ +/** + * Find the positive roots of a polynomial. + * @param[in] poly The coefficients of the polynomial to solve. + * @param[in] degree The degree of the polynomial. + * @param[out] x An array in which to store the roots. It should have + * dimension \p degree. + * @return The number of positive roots stored in \c x[]. + */ size_t dmnsn_solve_polynomial(const double poly[], size_t degree, double x[]); -/* Helper function to print a polynomial */ +/** + * Output a polynomial. The polynomial is printed as a function of x suitable + * for input into a CAS, and without a trailing newline. + * @param[in,out] file The file to write to. + * @param[in] poly The coefficients of the polynomial to print. + * @param[in] degree The degree of the polynomial. + */ void dmnsn_print_polynomial(FILE *file, const double poly[], size_t degree); #endif /* DIMENSION_POLYNOMIAL_H */ |