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/*
* Locates the first zero of a function in a given interval.
*
*/
/*
* 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
*
*/
char zero_premier_C[] = "$Header: /cvsroot/Lorene/C++/Source/Non_class_members/Utilities/zero_premier.C,v 1.3 2014/10/13 08:53:32 j_novak Exp $" ;
/*
* $Id: zero_premier.C,v 1.3 2014/10/13 08:53:32 j_novak Exp $
* $Log: zero_premier.C,v $
* Revision 1.3 2014/10/13 08:53:32 j_novak
* Lorene classes and functions now belong to the namespace Lorene.
*
* Revision 1.2 2002/10/16 14:37:12 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 1.2 2000/01/04 10:57:51 eric
* Le test f1*f2 < 0. est remplace par f1*f2 <= double(0).
*
* Revision 1.1 1999/12/24 13:00:10 eric
* Initial revision
*
*
* $Header: /cvsroot/Lorene/C++/Source/Non_class_members/Utilities/zero_premier.C,v 1.3 2014/10/13 08:53:32 j_novak Exp $
*
*/
// Headers Lorene
#include "headcpp.h"
#include "param.h"
//****************************************************************************
namespace Lorene {
bool zero_premier(double (*f)(double, const Param&), const Param& par,
double a, double b, int n, double& a0, double& b0) {
double dx = (b-a)/double(n) ;
a0 = a ;
b0 = a0 + dx ;
double f1 = f(a0, par) ;
bool trouve = false ;
for (int i=0; i<n; i++) {
double f2 = f(b0, par) ;
if (f1*f2 <= double(0)) { // on a encadre le zero
trouve = true ;
break ;
}
// On passe au sous-intervalle suivant :
a0 = b0 ;
f1 = f2 ;
b0 += dx ;
}
return trouve ;
}
}
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