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/*
Copyright 2012 Thibaut Paumard
This file is part of Gyoto.
Gyoto 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.
Gyoto 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 Gyoto. If not, see <http://www.gnu.org/licenses/>.
*/
#include "GyotoFunctors.h"
#include "GyotoError.h"
#include <cmath>
#include <cfloat>
#include <iostream>
#define dr_tol 1e-5
#define f_tol 1e-9
#define sign(a) (a>=0?1:-1)
Gyoto::Functor::Double_constDoubleArray::~Double_constDoubleArray() {}
Gyoto::Functor::Double_Double_const::~Double_Double_const() {}
double Gyoto::Functor::Double_Double_const::ridders(double r1, double r2) const
{
// Ridders' root-finding method applied to operator()
double val1 = operator()(r1);
double val2 = operator()(r2);
double r3, r4, val3, val4;
do {
r3 = 0.5*(r1+r2);
val3 = operator()(r3);
r4 = r3+(r3-r1) * sign(val1-val2)*val3/sqrt(val3*val3-val1*val2);
val4 = operator()(r4);
if (sign(val3)!=sign(val4)) {
// use r3 and r4 for next iteration
r1=r3; val1=val3;
r2=r4; val2=val4;
} else if (sign(val1) != sign(val4)) {
// use r1 and r4 for next iteration
r2=r4; val2=val4;
} else {
// use r4 and r2 for next iteration
r1=r4; val1=val4;
}
} while (fabs(r1-r2) >= dr_tol && fabs(val4) > f_tol) ;
return r4;
}
double Gyoto::Functor::Double_Double_const::secant(double r1, double r2)
{
// Secant root-finding method applied to operator()
double val1 = operator()(r1);
double val2 = operator()(r2);
double r3, val3=DBL_MAX;
unsigned int maxiter=20, iter;
for (iter = 0; iter < maxiter; ++iter) {
r3=r1-val1*(r2-r1)/(val2-val1);
val3 = operator()(r3);
if (fabs(r2-r3) <= fabs(r1-r3)) {
r1=r3; val1=val3;
} else {
r2=r3; val2=val3;
}
if ( (fabs(r1-r2) < dr_tol) || (fabs(val3) < f_tol) ) break;
if (val2==val1) {
status=1;
return r3;
}
}
if (iter==maxiter) {
status=2;
return r3;
}
status=0;
return r3;
}
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