LORENE
int1d_cheb.C
1 /*
2  * Copyright (c) 1999-2001 Eric Gourgoulhon
3  *
4  * This file is part of LORENE.
5  *
6  * LORENE is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License as published by
8  * the Free Software Foundation; either version 2 of the License, or
9  * (at your option) any later version.
10  *
11  * LORENE is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14  * GNU General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public License
17  * along with LORENE; if not, write to the Free Software
18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
19  *
20  */
21 
22 
23 char int1d_cheb_C[] = "$Header: /cvsroot/Lorene/C++/Source/Non_class_members/Operators/int1d_cheb.C,v 1.2 2014/10/13 08:53:23 j_novak Exp $" ;
24 
25 /*
26  * Calcul de l'integrale
27  *
28  * int_-1^1 f(x) dx (1)
29  *
30  * pour une fonction f(x) donnee par ses coefficients de Tchebyshev
31  *
32  * f(x) = som_{i=0}^{nr-1} c_i T_{i}(x) (2)
33  *
34  * Entree:
35  * ------
36  * int nr : Nombre de coefficients de Tchebyshev dans le
37  * developpement (2)
38  * const double* cf : Tableau des nr coefficients c_i de la fonction
39  * definis par (2). Le stokage doit etre le suivant
40  * cf[i] = c_i 0 <= i <= nr - 1
41  * L'espace memoire correspondant au pointeur cf doit
42  * etre de taille au moins nr et doit avoir ete
43  * alloue avant l'appel a la routine
44  *
45  * Sortie (valeur de retour) :
46  * ------
47  * double int1d_cheb : Valeur de l'integrale (1)
48  *
49  */
50 
51 /*
52  * $Id: int1d_cheb.C,v 1.2 2014/10/13 08:53:23 j_novak Exp $
53  * $Log: int1d_cheb.C,v $
54  * Revision 1.2 2014/10/13 08:53:23 j_novak
55  * Lorene classes and functions now belong to the namespace Lorene.
56  *
57  * Revision 1.1 2005/02/16 15:27:55 m_forot
58  * *** empty log message ***
59  *
60  *
61  * $Header: /cvsroot/Lorene/C++/Source/Non_class_members/Operators/int1d_cheb.C,v 1.2 2014/10/13 08:53:23 j_novak Exp $
62  *
63  */
64 
65 namespace Lorene {
66 
67 //*****************************************************************************
68 
69 double int1d_cheb(int nr, const double* cf){
70 
71  double som = - cf[0] ;
72  const double* cc = cf + 2 ;
73 
74  for (int i=2; i<nr ; i=i+2) {
75  som += *cc / (i*i - 1) ;
76  cc = cc + 2 ;
77  }
78 
79  return -2*som ;
80 
81 }
82 }
Lorene prototypes.
Definition: app_hor.h:64