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{ ******************************************************************
Brackets a minimum of a function
****************************************************************** }
unit uminbrak;
interface
uses
utypes, uminmax;
procedure MinBrack(Func : TFunc; var A, B, C, Fa, Fb, Fc : Float);
implementation
procedure MinBrack(Func : TFunc; var A, B, C, Fa, Fb, Fc : Float);
{ ------------------------------------------------------------------
Given two points (A, B) this procedure finds a triplet (A, B, C)
such that:
1) A < B < C
2) A, B, C are within the golden ratio
3) Func(B) < Func(A) and Func(B) < Func(C).
The corresponding function values are returned in Fa, Fb, Fc
------------------------------------------------------------------ }
begin
if A > B then
FSwap(A, B);
Fa := Func(A);
Fb := Func(B);
if Fb > Fa then
begin
FSwap(A, B);
FSwap(Fa, Fb);
end;
C := B + GOLD * (B - A);
Fc := Func(C);
while Fc < Fb do
begin
A := B;
B := C;
Fa := Fb;
Fb := Fc;
C := B + GOLD * (B - A);
Fc := Func(C);
end;
if A > C then
begin
FSwap(A, C);
FSwap(Fa, Fc);
end;
end;
end.
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