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//static const char* sccsid = "@(#)math_BracketMinimum.cxx 3.2 95/01/10"; // Do not delete this line. Used by sccs.
#include <math_BracketMinimum.ixx>
#include <StdFail_NotDone.hxx> // waiting for NotDone Exception
#include <math_Function.hxx>
#define GOLD 1.618034
#define CGOLD 0.3819660
#define GLIMIT 100.0
#define TINY 1.0e-20
#ifdef MAX
#undef MAX
#endif
#define MAX(a,b) ((a) > (b) ? (a) : (b))
#define SIGN(a,b) ((b) > 0.0 ? fabs(a) : -fabs(a))
#define SHFT(a,b,c,d) (a)=(b);(b)=(c);(c)=(d)
void math_BracketMinimum::Perform(math_Function& F,
const Standard_Real A,
const Standard_Real B) {
Standard_Boolean OK;
Standard_Real ulim, u, r, q, f, fu, dum;
Done = Standard_False;
Ax = A;
Bx = B;
Standard_Real Lambda = GOLD;
if (!myFA) {
OK = F.Value(Ax, FAx);
if(!OK) return;
}
if (!myFB) {
OK = F.Value(Bx, FBx);
if(!OK) return;
}
if(FBx > FAx) {
SHFT(dum, Ax, Bx, dum);
SHFT(dum, FBx, FAx, dum);
}
Cx = Bx + Lambda * (Bx - Ax);
OK = F.Value(Cx, FCx);
if(!OK) return;
while(FBx > FCx) {
r = (Bx - Ax) * (FBx -FCx);
q = (Bx - Cx) * (FBx -FAx);
u = Bx - ((Bx - Cx) * q - (Bx - Ax) * r) /
(2.0 * SIGN(MAX(fabs(q - r), TINY), q - r));
ulim = Bx + GLIMIT * (Cx - Bx);
if((Bx - u) * (u - Cx) > 0.0) {
OK = F.Value(u, fu);
if(!OK) return;
if(fu < FCx) {
Ax = Bx;
Bx = u;
FAx = FBx;
FBx = fu;
Done = Standard_True;
return;
}
else if(fu > FBx) {
Cx = u;
FCx = fu;
Done = Standard_True;
return;
}
u = Cx + Lambda * (Cx - Bx);
OK = F.Value(u, fu);
if(!OK) return;
}
else if((Cx - u) * (u - ulim) > 0.0) {
OK = F.Value(u, fu);
if(!OK) return;
if(fu < FCx) {
SHFT(Bx, Cx, u, Cx + GOLD * (Cx - Bx));
OK = F.Value(u, f);
if(!OK) return;
SHFT(FBx, FCx, fu, f);
}
}
else if ((u - ulim) * (ulim - Cx) >= 0.0) {
u = ulim;
OK = F.Value(u, fu);
if(!OK) return;
}
else {
u = Cx + GOLD * (Cx - Bx);
OK = F.Value(u, fu);
if(!OK) return;
}
SHFT(Ax, Bx, Cx, u);
SHFT(FAx, FBx, FCx, fu);
}
Done = Standard_True;
}
math_BracketMinimum::math_BracketMinimum(math_Function& F,
const Standard_Real A,
const Standard_Real B) {
myFA = Standard_False;
myFB = Standard_False;
Perform(F, A, B);
}
math_BracketMinimum::math_BracketMinimum(math_Function& F,
const Standard_Real A,
const Standard_Real B,
const Standard_Real FA) {
FAx = FA;
myFA = Standard_True;
myFB = Standard_False;
Perform(F, A, B);
}
math_BracketMinimum::math_BracketMinimum(math_Function& F,
const Standard_Real A,
const Standard_Real B,
const Standard_Real FA,
const Standard_Real FB) {
FAx = FA;
FBx = FB;
myFA = Standard_True;
myFB = Standard_True;
Perform(F, A, B);
}
void math_BracketMinimum::Values(Standard_Real& A, Standard_Real& B, Standard_Real& C) const{
StdFail_NotDone_Raise_if(!Done, " ");
A = Ax;
B = Bx;
C = Cx;
}
void math_BracketMinimum::FunctionValues(Standard_Real& FA, Standard_Real& FB, Standard_Real& FC) const{
StdFail_NotDone_Raise_if(!Done, " ");
FA = FAx;
FB = FBx;
FC = FCx;
}
void math_BracketMinimum::Dump(Standard_OStream& o) const {
o << "math_BracketMinimum ";
if(Done) {
o << " Status = Done \n";
o << " The bracketed triplet is: " << endl;
o << Ax << ", " << Bx << ", " << Cx << endl;
o << " The corresponding function values are: "<< endl;
o << FAx << ", " << FBx << ", " << FCx << endl;
}
else {
o << " Status = not Done \n";
}
}
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