Algorithm 2D Referential traduction

if x < 0
new x = (x - xmin) * (250 / (xmax - xmin)) ?

for (int xcanvas = 0; xcanvas <= 250; i++) {
    double x = ((xmax - xmin) * xcanvas / 250.0) + xmin;
    double y = f(x);

    int ycanvas = 250 * (y - ymin) / (ymax - ymin) + .5;

    // Plot (xcanvas, ycanvas)
}

(canvas_x, canvas_y) -> (maths_x, maths_y)
(maths_x, maths_y)   -> (canvas_x, canvas_y)

maths_x -> maths_y

maths_x = maths_x_from_canvas_x(canvas_x, min_maths_x, max_maths_x)
maths_y = maths_y_from_maths_x(maths_x) # this is the function to be plotted.
canvas_y = canvas_y_from_maths_y(maths_y, min_maths_y, max_maths_y)

if (canvas_y not out of bounds) plot(canvas_x, canvas_y)