diff options
Diffstat (limited to 'gsl-1.9/cheb/eval.c')
| -rw-r--r-- | gsl-1.9/cheb/eval.c | 206 |
1 files changed, 206 insertions, 0 deletions
diff --git a/gsl-1.9/cheb/eval.c b/gsl-1.9/cheb/eval.c new file mode 100644 index 0000000..9d5acda --- /dev/null +++ b/gsl-1.9/cheb/eval.c @@ -0,0 +1,206 @@ +/* cheb/eval.c + * + * Copyright (C) 1996, 1997, 1998, 1999, 2000 Gerard Jungman + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or (at + * your option) any later version. + * + * This program 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 + * General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. + */ + +#include <config.h> +#include <stdlib.h> +#include <gsl/gsl_math.h> +#include <gsl/gsl_errno.h> +#include <gsl/gsl_chebyshev.h> + +/* For efficiency there are separate implementations of each of these + functions */ + +double +gsl_cheb_eval (const gsl_cheb_series * cs, const double x) +{ + size_t i; + double d1 = 0.0; + double d2 = 0.0; + + double y = (2.0 * x - cs->a - cs->b) / (cs->b - cs->a); + double y2 = 2.0 * y; + + for (i = cs->order; i >= 1; i--) + { + double temp = d1; + d1 = y2 * d1 - d2 + cs->c[i]; + d2 = temp; + } + + return y * d1 - d2 + 0.5 * cs->c[0]; +} + +double +gsl_cheb_eval_n (const gsl_cheb_series * cs, const size_t n, const double x) +{ + size_t i; + double d1 = 0.0; + double d2 = 0.0; + + size_t eval_order = GSL_MIN (n, cs->order); + + double y = (2.0 * x - cs->a - cs->b) / (cs->b - cs->a); + double y2 = 2.0 * y; + + for (i = eval_order; i >= 1; i--) + { + double temp = d1; + d1 = y2 * d1 - d2 + cs->c[i]; + d2 = temp; + } + + return y * d1 - d2 + 0.5 * cs->c[0]; +} + + +int +gsl_cheb_eval_err (const gsl_cheb_series * cs, const double x, + double *result, double *abserr) +{ + size_t i; + double d1 = 0.0; + double d2 = 0.0; + + double y = (2. * x - cs->a - cs->b) / (cs->b - cs->a); + double y2 = 2.0 * y; + + double absc = 0.0; + + for (i = cs->order; i >= 1; i--) + { + double temp = d1; + d1 = y2 * d1 - d2 + cs->c[i]; + d2 = temp; + } + + *result = y * d1 - d2 + 0.5 * cs->c[0]; + + /* Estimate cumulative numerical error */ + + for (i = 0; i <= cs->order; i++) + { + absc += fabs(cs->c[i]); + } + + /* Combine truncation error and numerical error */ + + *abserr = fabs (cs->c[cs->order]) + absc * GSL_DBL_EPSILON; + + return GSL_SUCCESS; +} + +int +gsl_cheb_eval_n_err (const gsl_cheb_series * cs, + const size_t n, const double x, + double *result, double *abserr) +{ + size_t i; + double d1 = 0.0; + double d2 = 0.0; + + double y = (2. * x - cs->a - cs->b) / (cs->b - cs->a); + double y2 = 2.0 * y; + + double absc = 0.0; + + size_t eval_order = GSL_MIN (n, cs->order); + + for (i = eval_order; i >= 1; i--) + { + double temp = d1; + d1 = y2 * d1 - d2 + cs->c[i]; + d2 = temp; + } + + *result = y * d1 - d2 + 0.5 * cs->c[0]; + + /* Estimate cumulative numerical error */ + + for (i = 0; i <= eval_order; i++) + { + absc += fabs(cs->c[i]); + } + + /* Combine truncation error and numerical error */ + + *abserr = fabs (cs->c[eval_order]) + absc * GSL_DBL_EPSILON; + + return GSL_SUCCESS; +} + +int +gsl_cheb_eval_mode_e (const gsl_cheb_series * cs, + const double x, gsl_mode_t mode, + double *result, double *abserr) +{ + size_t i; + double d1 = 0.0; + double d2 = 0.0; + + double y = (2. * x - cs->a - cs->b) / (cs->b - cs->a); + double y2 = 2.0 * y; + + double absc = 0.0; + + size_t eval_order; + + if (GSL_MODE_PREC (mode) == GSL_PREC_DOUBLE) + eval_order = cs->order; + else + eval_order = cs->order_sp; + + for (i = eval_order; i >= 1; i--) + { + double temp = d1; + d1 = y2 * d1 - d2 + cs->c[i]; + d2 = temp; + } + + *result = y * d1 - d2 + 0.5 * cs->c[0]; + + /* Estimate cumulative numerical error */ + + for (i = 0; i <= eval_order; i++) + { + absc += fabs(cs->c[i]); + } + + /* Combine truncation error and numerical error */ + + *abserr = fabs (cs->c[eval_order]) + absc * GSL_DBL_EPSILON; + + return GSL_SUCCESS; +} + +double +gsl_cheb_eval_mode (const gsl_cheb_series * cs, + const double x, gsl_mode_t mode) +{ + double result, abserr; + int status = gsl_cheb_eval_mode_e (cs, x, mode, &result, &abserr); + + if (status != GSL_SUCCESS) + { + GSL_ERROR_VAL("gsl_cheb_eval_mode", status, result); + }; + + return result; +} + + |