You can apply a scale/bias function to x and y values.
double x, y;
double width = panel.Width / 2d;
double height = panel.Height / 2d;
double newX = x * width;
newX += width;
double newY = y * height;
newY += height;
In case your panel is not square, and you do not want the resulting curve to be distorded, then you have to choose the least between both factors width and height, and use this one as the scaling factor for x and y.
Hope this helps. Kindly.