This little app show (in color!) the solutions of a system of equations (when the system equals [0, 0]).
The first two frames are respectively the input and the output. We calculate each output coordinates (from [Xmin, Ymin] to [Xmax, Ymax]), to retrieve the corresponding color, and then we put this color onto the input.
This shows from which input we get a [0, 0] couple!
If you click the 'show' button, a graph corresponding to Z = f(x, y) will be drawn underneath, with Z in greyscale. This will also set the Z min and max, which is needed to draw correctly the first frame.
If you think that the black spot is not narrow enougth, you can play with the 'Saturation magnitude' (don't forget to update the output frame).
Here are some examples to get started : (As you can see, on the first example, circle, there seems to be two solutions, but that's because we are searching for any couple that produce [100, 0] (and that's [±10, 0]). Pay attention to your axes !)