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/*
* Copyright (c) 2005 Jerome Novak
*
* This file is part of LORENE.
*
* LORENE 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.
*
* LORENE 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 LORENE; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
char int1d_chebi_C[] = "$Header: /cvsroot/Lorene/C++/Source/Non_class_members/Operators/int1d_chebi.C,v 1.4 2014/10/13 08:53:23 j_novak Exp $" ;
/*
* Calcul de l'integrale
*
* int_0^1 f(x) dx (1)
*
* pour une fonction f(x) paire donnee par ses coefficients de Tchebyshev
*
* f(x) = som_{i=0}^{nr-1} c_i T_{2i+1}(x) (2)
*
* Entree:
* ------
* int nr : Nombre de coefficients de Tchebyshev dans le
* developpement (2)
* const double* cf : Tableau des nr coefficients c_i de la fonction
* definis par (2). Le stokage doit etre le suivant
* cf[i] = c_i 0 <= i <= nr - 1
* L'espace memoire correspondant au pointeur cf doit
* etre de taille au moins nr et doit avoir ete
* alloue avant l'appel a la routine
*
* Sortie (valeur de retour) :
* ------
* double int1d_chebi : Valeur de l'integrale (1)
*
*/
/*
* $Id: int1d_chebi.C,v 1.4 2014/10/13 08:53:23 j_novak Exp $
* $Log: int1d_chebi.C,v $
* Revision 1.4 2014/10/13 08:53:23 j_novak
* Lorene classes and functions now belong to the namespace Lorene.
*
* Revision 1.3 2005/11/02 15:08:18 j_novak
* Minor change to prevent warning message.
*
* Revision 1.2 2005/05/13 13:22:33 j_novak
* *** empty log message ***
*
* Revision 1.1 2005/05/13 08:51:02 j_novak
* Added the function int1d_chebi.
*
*
* $Header: /cvsroot/Lorene/C++/Source/Non_class_members/Operators/int1d_chebi.C,v 1.4 2014/10/13 08:53:23 j_novak Exp $
*
*/
namespace Lorene {
//*****************************************************************************
double int1d_chebi(int nr, const double* cf){
double som = 0. ;
const double* cc = cf ;
for (int i=0; i<nr-2 ; i+=2) {
som += (cc[0] - cc[1] ) / double(2*i + 2) ;
cc += 2 ;
}
if (nr%2 == 0) som += (*cc) / double(2*nr - 2) ;
return som ;
}
}
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