Eine ganzzahl herrausfinden?

[marabu]

Besser so:

Delphi-Quellcode:

const
  INFIMUM = -100;
  MAXIMUM = 1000;
  EPSILON = 1E-8;
  STEP = 1E-4;

function F(x: Double): Double;
var
  r: Double;
begin
  r := 39 / 25 * x * x - 19;
  if r < 0
    then Result := NaN
    else Result := (-8/5) * x + Sqrt(r);
end;

procedure TDemoForm.Button14Click(Sender: TObject);
var
  x, y: Double;
begin
  x := INFIMUM;
  repeat
    x := x + STEP;
    y := F(x);
  until IsNaN(y) or (x > MAXIMUM) or IsZero(y - Round(y), EPSILON);
  if IsNaN(y)
    then ShowMessage('rats')
    else ShowMessage(Format('x = %0.4f   y = %.4f', [x, y]));
end;

Analysiere die Unterschiede.