Items tagged with lyapunov



Is it possible to solve linear matrix inequality in Maple?
For example, using Matlab and yalmip we can easily
solve Lyapunov equation
    A'P + P * A <0, P> 0

Is it possible to solve this equation in the Maple?



The following (downsized) images of Lyapunov fractals were each generated in a few seconds, in Maple 16.


I may make an interface for this with embedded components, or submit it in some form on the Application Center. But I thought that I'd share this version here first.

I'm just re-using the techniques in the code behind an earlier Post on Mandelbrot and Julia fractals. But I've only used one simple coloring scheme here, so far. I'll probably try the so-called burning ship escape-time fractal next.





Here below is the contents of the worksheet attached at the end of this Post.



The procedures are defined in the Startup code region of this worksheet.


It should run in Maple 15 and 16, but may not work in earlier versions since it relies on a properly functioning Threads:-Task.


The procedure `Lyapunov` can be called as


          Lyapunov(W, xa, xb, ya, yb, xresolution)

          Lyapunov(W, xa, xb, ya, yb, xresolution, numterms=N)


where those parameters are,


 - W, a Vector or list whose entries should be only 0 or 1

 - xa, the leftmost x-point (a float, usually greater than 2.0)

 - xb, the rightmost x-point (a float, usually less than or equal to 4.0)

 - ya, the lowest y-point (a float, usually greater than 2.0)

 - yb, the highest y-point (a float, usually less than or equal to 4.0)

 - xresolution, the width in pixels of the returned image (Array)

 - numterms=N, (optional) where positive integer N is the number of terms added for the approx. Lyapunov exponent



The speed of calculation depends on whether the Compiler  is functional and how many cores are detected. On a 4-core Intel i7 under Windows 7 the first example below had approximately the following performce in 64bit Maple 16.





serial (1 core)

20 seconds

240 seconds

parallel (4 cores)

5 seconds

60 seconds





res1:=CodeTools:-Usage( Lyapunov(W, 2.01, 4.0, 2.01, 4.0, 500) ):

memory used=46.36MiB, alloc change=65.73MiB, cpu time=33.87s, real time=5.17s


res2:=CodeTools:-Usage( Lyapunov(W, 2.5, 3.4, 3.4, 4.0, 500) ):

memory used=30.94MiB, alloc change=0 bytes, cpu time=21.32s, real time=3.54s


res3:=CodeTools:-Usage( Lyapunov(W, 2.1, 3.7, 3.1, 4.0, 500) ):

memory used=26.18MiB, alloc change=15.09MiB, cpu time=18.44s, real time=2.95s


res4:=CodeTools:-Usage( Lyapunov(W, 2.01, 4.0, 2.01, 4.0, 500) ):

memory used=46.25MiB, alloc change=15.09MiB, cpu time=33.52s, real time=5.18s





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