"Floating point overflow" error in Delphi code

debugging, delphi

Solution

Look here: `V[i][j]:= 5 * V[i][j] + 2.0 * Random;`

You make 2000 iterations, so your results might be as large as 7^2000 ~ 10^1690, but max value for Double type is about 10^308. So “Floating point overflow” error is exact diagnosis.

You could see V[] values about 10^307 in debug watch or immediate watch (mouse over V[]) when error occurred.

You can use 10-byte Extended type(probably not available for 64-bit compilers) to avoid overflow for these given variable values, but this is not good solution in general case.

Aside note: You did not set i index value for this code piece:

for j:=0 to d-1 do
  begin
    X[i][j]:= Lower + (Upper - Lower) * Random;
    V[i][j] := 0.1 * X[i][j];
  end;

Problem

I have this source code in Delphi, why I get this error "Floating point overflow." when I run the code? and how to correct it? The error message: The code: ``` procedure TForm1.Button1Click(Sender: TObject); var n, d, i, j, maxiter , iter: Integer; Lower,Upper : Double; X, V : TArray<TArray<Double>>; begin Lower := 0; Upper := 0.2; n := 100; d := 55; SetLength(V, n, d); SetLength(X, n, d); maxiter := 2000; iter := 1; for i:= 0 n-1 do for j:=0 to d-1 do begin X[i][j]:= Lower + (Upper - Lower) * Random; V[i][j] := 0.1 * X[i][j]; end; while (iter <= maxiter) do begin for i:= 0 to n-1 do for j:= 0 to D-1 do V[i][j]:= 5 * V[i][j] + 2.0 * Random; iter := iter +1; end; end; ```

Original source