const float inv2PI = 1./ sqrt(2*PI);    float Gaussian(float x, float mean=0.0, float dev=1.0)
{ float result;      result = inv2PI/dev * exp( -0.5* (x-mean)*(x-mean)/(dev*dev) );      return result;
}    void drawGaussian(TCanvas *canvas, int x0, int y0, float scale=20)
{ int px, py;
  int index=0, dx=1;
  float range=13, x=-range, dr=0.05;      canvas->MoveTo(x0-5, y0);
  canvas->LineTo(x0 dx*2*range/dr 5, y0);
  canvas->MoveTo(x0, y0-scale*Gaussian(x) );      canvas->MoveTo(x0 dx*range/dr, y0);
  canvas->LineTo(x0 dx*range/dr, y0-scale-5);      canvas->MoveTo(x0, y0-scale*Gaussian(x));
  canvas->Pen->Color = clRed;
  for (; x<=range; x =dr)
     { px = (int)(x0   index);
       py = (int)(y0 - scale*Gaussian(x) );
       if ( x==0.0 )
         { TPoint pt = canvas->PenPos;
           canvas->MoveTo(px, y0);
           canvas->LineTo(px, y0-scale-5);
           canvas->MoveTo(pt.x, pt.y);
         }
       canvas->LineTo(px,py);
       index  = dx;
     }
}    void __fastcall TForm1::FormPaint(TObject *Sender)
{
  drawGaussian(Form1->Canvas, 10, 200, 180);
}
//---------------------------------------------------------------------------