div_cos_1d.cpp

/*
    Copyright 2017 Philippe Grandclement
 
    This file is part of Kadath.
 
    Kadath 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 3 of the License, or
    (at your option) any later version.
 
    Kadath 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 Kadath.  If not, see <http://www.gnu.org/licenses/>.
*/
 
#include "base_spectral.hpp"
#include "headcpp.hpp"
#include "array.hpp"
namespace Kadath {
int div_cos_1d_pasprevu (Array<double>&) {
    cout << "div_cos_1d not implemented." << endl ;
    abort() ;
} 
 
int div_cos_1d_cos_even (Array<double>& tab) {
    assert (tab.get_ndim()==1) ;
    int nr = tab.get_size(0) ;
 
    Array<double> res (nr) ;
 
    double somme = 0 ;  
    res.set(nr-1) = 0. ;
    int signe = 1 ;
    for (int k=nr-2; k>=0; k--) {
        somme -= 2*signe*tab(k+1) ;
        signe *= -1 ;
        res.set(k) = (k%2==0) ? somme : -somme;
        }
    tab = res ;
    return COS_ODD ;
}
 
int div_cos_1d_sin_odd (Array<double>& tab) {
    assert (tab.get_ndim()==1) ;
    int nr = tab.get_size(0) ;
 
    Array<double> res (nr) ;
 
    double somme = 0 ;  
    res.set(nr-1) = 0. ;
    int signe = -1 ;
    for (int k=nr-2; k>0; k--) {
        somme -= 2*signe*tab(k) ;
        signe *= -1 ;
        res.set(k) = (k%2==0) ? -somme : +somme ;
    }
 
    tab = res ;
    return SIN_EVEN ;
}
 
int div_cos_1d_cos_odd (Array<double>& tab) {
    assert (tab.get_ndim()==1) ;
    int nr = tab.get_size(0) ;
 
    Array<double> res (nr) ;
 
    double somme = 0 ;  
    res.set(nr-1) = 0. ;
    int signe = -1 ;
    for (int k=nr-2; k>=0; k--) {
        somme += 2*tab(k)*signe ;
        res.set(k) = (k%2==0) ? somme : -somme;
        signe *= -1 ;
        }
    res.set(0) *= 0.5 ;
    tab = res ;
    return COS_EVEN ;
}
 
int div_cos_1d_sin_even (Array<double>& tab) {
    assert (tab.get_ndim()==1) ;
    int nr = tab.get_size(0) ;
 
    Array<double> res (nr) ;
 
    double somme = 0 ;
    int signe = -1 ;
    res.set(nr-1) = 0. ;
    for (int k=nr-2; k>=0; k--) {
        somme -= 2*tab(k+1)*signe ;
        signe *= -1 ;
        res.set(k) = (k%2==0) ? -somme : somme;
        }
    tab = res ;
    return SIN_ODD ;
}
 
int div_cos_1d (int base, Array<double>& tab) {
    static int (*div_cos_1d[NBR_MAX_BASE])(Array<double>&) ;
    static bool premier_appel = true ;
    
    // Premier appel
    if (premier_appel) {
    premier_appel = false ;
 
    for (int i=0; i<NBR_MAX_BASE; i++)
        div_cos_1d[i] = div_cos_1d_pasprevu ;
 
    div_cos_1d[COS_EVEN] = div_cos_1d_cos_even ;
    div_cos_1d[SIN_ODD] = div_cos_1d_sin_odd ;
    div_cos_1d[COS_ODD] = div_cos_1d_cos_odd ;
    div_cos_1d[SIN_EVEN] = div_cos_1d_sin_even ;
    }
    
        return div_cos_1d[base](tab) ;
}}