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//static const char* sccsid = "@(#)math_NewtonFunctionRoot.cxx 3.2 95/01/10"; // Do not delete this line. Used by sccs.
#include <math_NewtonFunctionRoot.ixx>
#include <math_FunctionWithDerivative.hxx>
math_NewtonFunctionRoot::math_NewtonFunctionRoot (math_FunctionWithDerivative& F,
const Standard_Real Guess,
const Standard_Real EpsX ,
const Standard_Real EpsF ,
const Standard_Real A,
const Standard_Real B,
const Standard_Integer NbIterations ){
EpsilonX = EpsX;
EpsilonF = EpsF;
Binf = A;
Bsup = B;
Itermax = NbIterations;
Done = Standard_False;
X = RealLast();
DFx = 0;
Fx = RealLast();
It = 0;
Perform(F, Guess);
}
math_NewtonFunctionRoot::math_NewtonFunctionRoot (const Standard_Real A ,
const Standard_Real B,
const Standard_Real EpsX ,
const Standard_Real EpsF ,
const Standard_Integer NbIterations ){
Binf = A;
Bsup = B;
EpsilonX = EpsX;
EpsilonF = EpsF;
Itermax = NbIterations;
Done = Standard_False;
X = RealLast();
DFx = 0;
Fx = RealLast();
It = 0;
}
math_NewtonFunctionRoot::math_NewtonFunctionRoot (math_FunctionWithDerivative& F,
const Standard_Real Guess,
const Standard_Real EpsX ,
const Standard_Real EpsF ,
const Standard_Integer NbIterations ){
EpsilonX = EpsX;
EpsilonF = EpsF;
Itermax = NbIterations;
Binf = RealFirst();
Bsup = RealLast();
Done = Standard_False;
X = RealLast();
DFx = 0;
Fx = RealLast();
It = 0;
Perform(F, Guess);
}
void math_NewtonFunctionRoot::Perform(math_FunctionWithDerivative& F,
const Standard_Real Guess) {
Standard_Real Dx;
Standard_Boolean Ok;
Standard_Real AA, BB;
//--------------------------------------------------
//-- lbr le 12 Nov 97
//-- la meilleure estimation n est pas sauvee et on
//-- renvoie une solution plus fausse que Guess
Standard_Real BestX=X,BestFx=RealLast();
//--
if ( Binf < Bsup) {
AA = Binf;
BB = Bsup;
}
else {
AA = Bsup;
BB = Binf;
}
Dx = RealLast();
Fx = RealLast();
X = Guess;
It = 1;
while ( (It <= Itermax) && ( (Abs(Dx) > EpsilonX) ||
(Abs(Fx) > EpsilonF) ) ) {
Ok = F.Values(X,Fx,DFx);
Standard_Real AbsFx = Fx; if(AbsFx<0) AbsFx=-AbsFx;
if(AbsFx<BestFx) {
BestFx=AbsFx;
BestX =X;
}
if (Ok) {
if (DFx == 0.) {
Done = Standard_False;
It = Itermax + 1;
}
else {
Dx = Fx/DFx;
X -= Dx;
// Limitation des variations de X:
if (X <= AA) X = AA;
if (X >= BB) X = BB;
It++;
}
}
else {
Done = Standard_False;
It = Itermax + 1;
}
}
X = BestX;
if (It <= Itermax) {
Done = Standard_True;
}
else
{
Done = Standard_False;
}
}
void math_NewtonFunctionRoot::Dump(Standard_OStream& o) const {
o <<"math_NewtonFunctionRoot ";
if (Done) {
o << " Status = Done \n";
o << " Location found = " << X <<"\n";
o << " function value at this minimum = " << Fx <<"\n";
o << " Number of iterations = " << It <<"\n";
}
else {
o << "Status = not Done \n";
}
}
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