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Ljapunow diagrams

Started by marcm200, 14:05, 17 July 22

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marcm200

I tried the Ljapunow diagrams (article by Mario Markus, Spektrum der Wissenschaft 1995) on the CPC to see how far I could get. The Ljapunows were one of my first large project back in the 90s (in TurboPascal and afterwards in C++). I lost the code several times, had to rewrite it over and over, so I now know it backwards :)

The CPC BASIC code here is a rudimentary implementation of two functions from a recent C++ project: https://github.com/marcm200/lyapunov-core

The ZIP contains a DSK-image, a manual on how to alter the code to get different parameters or functions, the parameter files (plain text) and screen memory dumps of the images below.

Two examples, computed in cpcemu (fast speed) - MODE 0, so they are more granular than the C++ controls but still computed as if 200x200 pixel existed - with 4 colors used (one could take more to get finer details appearing), a control by the C++ version, and a high-resolution image with linearly interpolated RGB-colors: ldn1 from https://www.deviantart.com/marcm200/gallery/67832833/lyapunov-images-original-algorithm

I was surprised to see how easy it was to code the routine in global scope without C++ structs or functions. The ON GOSUB is quite powerful here. Optimizations were only done in storing and reusing some intermediate results during calculation the function and derivative values.

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