File indexing completed on 2024-05-12 15:27:09

 /***************************************************************************
     File                 : nsl_sf_kernel.c
     Project              : LabPlot
     Description          : NSL special kernel functions
     --------------------------------------------------------------------
     Copyright            : (C) 2016 by Stefan Gerlach (stefan.gerlach@uni.kn)
 
  ***************************************************************************/
 
 /***************************************************************************
  *                                                                         *
  *  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 "nsl_sf_kernel.h"
 #include <stdlib.h>
 #include <math.h>
 #include <gsl/gsl_math.h>
 #include <gsl/gsl_randist.h>    /* Gaussian and Cauchy */
 
 /* kernel on [-1,1] */
 
 double nsl_sf_kernel_uniform(double u) {
     if(fabs(u) <= 1.0)
         return 0.5;
     return 0.0;
 }
 
 double nsl_sf_kernel_triangular(double u) {
     if(fabs(u) <= 1.0)
         return 1.0-fabs(u);
     return 0.0;
 }
 
 double nsl_sf_kernel_parabolic(double u) {
     if(fabs(u) <= 1.0)
         return 3./4.*(1.0-gsl_pow_2(u));
     return 0.0;
 }
 
 double nsl_sf_kernel_quartic(double u) {
     if(fabs(u) <= 1.0)
         return 15./16.*gsl_pow_2(1.0-gsl_pow_2(u));
     return 0.0;
 }
 
 double nsl_sf_kernel_triweight(double u) {
     if(fabs(u) <= 1.0)
         return 35./32.*gsl_pow_3(1.0-gsl_pow_2(u));
     return 0.0;
 }
 
 double nsl_sf_kernel_tricube(double u) {
     if(fabs(u) <= 1.0)
         return 70./81.*gsl_pow_3(1.0-gsl_pow_3(fabs(u)));
     return 0.0;
 }
 
 double nsl_sf_kernel_cosine(double u) {
     if(fabs(u) <= 1.0)
         return M_PI_4*cos(M_PI_2*u);
     return 0.0;
 }
 
 double nsl_sf_kernel_semicircle(double u) {
     if(fabs(u) < 1.0)
         return M_2_PI*sqrt(1-gsl_pow_2(u));
     return 0.0;
 }
 
 /* kernel on (-inf,inf) */
 double nsl_sf_kernel_gaussian(double u) {
     return gsl_ran_gaussian_pdf(u, 1.0);
 }
 
 double nsl_sf_kernel_cauchy(double u) {
     return gsl_ran_cauchy_pdf(u, 1.0);
 }
 
 double nsl_sf_kernel_logistic(double u) {
     return gsl_ran_logistic_pdf(u, 1.0);
 }
 
 double nsl_sf_kernel_picard(double u) {
     return 0.5*exp(-fabs(u));
 }
 
 double nsl_sf_kernel_sigmoid(double u) {
     return M_1_PI/cosh(u);
 }
 
 double nsl_sf_kernel_silverman(double u) {
     return 1.0/2.0*exp(-fabs(u)/M_SQRT2)*sin(fabs(u)/M_SQRT2+M_PI_4);
 }