Is there a (free) program or something online that can plot a complex function from one complex plane to another? Like in the picture below? I want to be able to see where numbers go, so to speak, with colors or something.

Is there a (free) program or something online that can plot a complex function from one complex plane to another? Like in the picture below? I want to be able to see where numbers go, so to speak, with colors or something.

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I have never found a satisfactory program for doing the kind of complex transformations you are talking about and have always resorted to doing my own programming (in Matlab, which handles complex number calculations seamlessly). To that end, I did a few quick and dirty calculations for you comparing two transformations. The first is a bilinear transform, shown the two images below.
The second is an exponential transform shown in the next two images
