Procedure ZBRAK(X1, X2:real; N:integer;
                        var XB1, XB2:array of real;var NB:integer);
var
    NBB,I:integer;   X,DX,FP,FC:real;
begin
    NBB:=NB;
    NB:=0;
    X:=X1;
    DX:=(X2 - X1) / N;
    FP:=FUN(X);
    For I:=1 To N do
    begin
        X:=X + DX;
        FC:=FUN(X);
        If FC * FP < 0  Then
        begin
            NB:=NB + 1;
            XB1[NB]:=X - DX;
            XB2[NB]:=X;
        end;
        FP:=FC;
        If NBB = NB Then Exit;
    end; 
end;