qrbksb.txt

Numeric Programs

procedure QRBKSB(A:matrx2; N:integer; Q:matrx2; B:array of real;
                                              var X:array of real);
var
    I,J:integer;  SUM:real;
begin
    For I:=1 To N do
    begin
        Sum:=0;
        For J:=1 To N do
            Sum:=Sum + Q[I, J] * B[J];
        X[I]:=Sum;
    end;
    For I:=N DownTo 1 do
    begin
        Sum:=X[I];
        For J:=I + 1 To N do
            Sum:=Sum - A[I, J] * X[J];
        If A[I, I] = 0 Then ShowMessage('A is singular matrix.');
        X[I]:=Sum / A[I, I];
    end;
end;