Chris@0: /*
Chris@0:   copyright (C) 2012 I. Irigaray, M. Rocamora
Chris@0: 
Chris@0:   This program is free software: you can redistribute it and/or modify
Chris@0:   it under the terms of the GNU General Public License as published by
Chris@0:   the Free Software Foundation, either version 3 of the License, or
Chris@0:   (at your option) any later version.
Chris@0: 
Chris@0:   This program is distributed in the hope that it will be useful,
Chris@0:   but WITHOUT ANY WARRANTY; without even the implied warranty of
Chris@0:   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
Chris@0:   GNU General Public License for more details.
Chris@0: 
Chris@0:   You should have received a copy of the GNU General Public License
Chris@0:   along with this program.  If not, see <http://www.gnu.org/licenses/>.
Chris@0:  */
Chris@0: 
Chris@0: 
Chris@0: #include "FChTransformUtils.h"
Chris@0: #include <math.h>
Chris@0: 
Chris@0: void cumtrapz(const double *x, const double *y, size_t N, double *accum)
Chris@0: /*Trapezoidal Integrator: 1/2(b-a)(F(a)+F(b))*/
Chris@0: {
Chris@0: 
Chris@0: accum[0]=0.0;
Chris@0: for (size_t i = 1; i < N; i++) {
Chris@0:     accum[i]=accum[i-1]+0.5*(x[i]-x[i-1])*(y[i]+y[i-1]);
Chris@0: }
Chris@0: 
Chris@0: }
Chris@0: 
Chris@0: 
Chris@0: void interp1(const double *x1, const double *y1, size_t N1, const double *x2, double *y2, size_t N2){
Chris@0: /*1-D linear interpolation*/
Chris@0: 
Chris@0: 	for (size_t i = 0; i < N2; i++) {
Chris@0: 		/*Smaller or equal than the smallest, or larger or equal than the largest.*/
Chris@0: 		if ( x2[i] <= x1[0] ) {
Chris@0: 			y2[i] = y1[0];
Chris@0: 		} else if ( x2[i] >= x1[N1-1] ) {
Chris@0: 			y2[i] = y1[N1-1];
Chris@0: 		} else {
Chris@0: 			/*Search every value of x2 in x1*/
Chris@0: 			size_t j = 1;
Chris@0: 			size_t salir = 0;
Chris@0: 			while ((j<N1)&&(!salir)) {			
Chris@0: 				if ( x2[i] <= x1[j] ) {
Chris@0: 					//y2[i] = ( x2[i]*( y1[j] - y1[j-1] ) + x1[j]*y1[j-1] - x1[j-1]*y1[j] ) / ( x1[j] - x1[j-1] );
Chris@0: 					y2[i] = y1[j-1] + ( ( y1[j] - y1[j-1] )*(x2[i] - x1[j-1] ) )/ ( x1[j] - x1[j-1] );
Chris@0: 					salir = 1;
Chris@0: 				} // if
Chris@0: 				j++;
Chris@0: 			} // for
Chris@0: 		} // else
Chris@0: 	} // for
Chris@0: 
Chris@0: }
Chris@0: 
Chris@0: void interp1q(const double *y1, const size_t *x2_int, const double *x2_frac, double *y2, size_t N2){
Chris@0: 
Chris@0: 	for(size_t i=0;i<N2;i++){
Chris@0: 		y2[i] = y1[x2_int[i]]*(1.0-x2_frac[i])+y1[x2_int[i]+1]*x2_frac[i];
Chris@0: 	} // for
Chris@0: 
Chris@0: }
Chris@0: 
Chris@0: void hanning_window(double *p_window, size_t n, bool normalize) {
Chris@0: 
Chris@0: 	double accum=0;
Chris@0:     for (size_t i = 0; i < n; i++) {
Chris@0:         p_window[i] = 0.5*(1.0-cos(2*M_PI*(double)(i+1)/((double)n+1.0)));
Chris@0:         accum += p_window[i];
Chris@0:     }
Chris@0: 	if (normalize) {
Chris@0:     	for (size_t i = 0; i < n; i++) { //window normalization
Chris@0:     		p_window[i] = p_window[i]/accum;
Chris@0:     	}
Chris@0: 	}
Chris@0: 
Chris@0: }