chebimp_ini.C

/*
 *   Copyright (c) 1999-2001 Eric Gourgoulhon
 *
 *   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
 *
 */


 


/* 
 * Routine de calcul des points de collocations 
 *
 *            x_i = sin( pi/2 i/(n-1) )    0 <= i <= n-1  
 *
 * des echantillonnages de [0, 1] rarefies en 0.  
 * Ces valeurs sont notamment utilisees pour les transformations de Tchebyshev 
 * impaires. 
 * 
 *
 * Entree:
 * -------
 *   const int n :  nombre de degres de liberte
 *
 * Sortie:
 * -------
 *   double* chebimp_ini :  pointeur sur la table des points de collocation
 *              L'espace memoire correspondant a ce pointeur
 *              est alloue par la routine.
 */

/*
 * $Id: chebimp_ini.C,v 1.7 2016/12/05 16:18:01 j_novak Exp $
 * $Log: chebimp_ini.C,v $
 * Revision 1.7  2016/12/05 16:18:01  j_novak
 * Suppression of some global variables (file names, loch, ...) to prevent redefinitions
 *
 * Revision 1.6  2014/10/13 08:53:11  j_novak
 * Lorene classes and functions now belong to the namespace Lorene.
 *
 * Revision 1.5  2014/10/06 15:16:01  j_novak
 * Modified #include directives to use c++ syntax.
 *
 * Revision 1.4  2005/02/18 13:14:12  j_novak
 * Changing of malloc/free to new/delete + suppression of some unused variables
 * (trying to avoid compilation warnings).
 *
 * Revision 1.3  2003/01/31 10:31:23  e_gourgoulhon
 * Suppressed the directive #include <malloc.h> for malloc is defined
 * in <stdlib.h>
 *
 * Revision 1.2  2002/10/16 14:36:53  j_novak
 * Reorganization of #include instructions of standard C++, in order to
 * use experimental version 3 of gcc.
 *
 * Revision 1.1.1.1  2001/11/20 15:19:29  e_gourgoulhon
 * LORENE
 *
 * Revision 2.1  1999/11/24  16:18:29  eric
 * Modif affichage.
 *
 * Revision 2.0  1999/02/22  15:44:12  hyc
 * *** empty log message ***
 *
 *
 * $Header: /cvsroot/Lorene/C++/Source/Non_class_members/Coef/chebimp_ini.C,v 1.7 2016/12/05 16:18:01 j_novak Exp $
 *
 */

// headers du C
#include <cassert>
#include <cmath>
#include <cstdlib>

#include "headcpp.h"

namespace Lorene {
//*****************************************************************************

double* chebimp_ini(const int n )
{

// Variables locales statiques
// ---------------------------
#define NMAX    30          /* Nombre maximun de dimensions differentes */
static  double* table_x[NMAX] ;     /* Tableau des pointeurs sur les tableaux */
static  int nwork = 0 ;     /* Nombre de tableaux deja initialises */
static  int tbn[NMAX] ;     /* Tableau des points deja initialises */
int indice ;

    // Mise en zone critique de toute la routine
    {
    // Ce nombre de points a-t-il deja ete utilise ?
    indice = -1 ;
    int i ;
    for ( i=0 ; i < nwork ; i++ ) {
    if ( tbn[i] == n ) indice = i ;
    }

    // Initialisation
    if (indice == -1) {         /* Il faut une nouvelle initialisation */
    if ( nwork >= NMAX ) {
        cout << "chebimp_ini: nwork > NMAX : "
        << nwork << " <-> " << NMAX << endl ;
        abort () ;  
        }
    indice = nwork ; nwork++ ; tbn[indice] = n ;

    table_x[indice] = new double[n] ; 

    double xx = M_PI / double(2*(n-1));
    for ( i = 0; i < n ; i++ ) {
        table_x[indice][i] = sin( xx * i );
        }
    }

    }       // Fin de la zone critique

    // Valeurs de retour
    return table_x[indice] ;

}
}