## 80 Reputation

10 years, 76 days

## Bug in contourplot?...

Maple

Hi everyone,

as a very basis example I've tried to get the equipotential lines of an 1/r² potential in the x-y-plane using contourplot. However, I obtained the following very strange result. Do you get the same mistake or is there something wrong on my end?

Sören

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## Error in the calculation of the arc leng...

Maple 2016

Good day!

As part of an exercise I've calculated the length of a hypotrochoid numerically. To check my result I repeated the calculation in Maple, but received a different result. When double checking using WolframAlpha I got the same result as with my numerics. Maybe someone of you can tell me where I made a mistake.

Sören

Link to WolframAlpha calculation: http://www.wolframalpha.com/input/?i=x%28t%29+%3D+%281-0.6%29+cos%28t%29+%2B+0.8+cos+%28+%281-0.6%29%2F0.6+*+t%29,+y%28t%29+%3D+%281-0.6%29+sin%28t%29+-+0.8+sin+%28+%281-0.6%29%2F0.6+*+t%29+from+t%3D0+to+6*pi

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## Strange result for the evaluation of a s...

Maple 18

Hello guys,

I was just playing around with the Shanks transformation of a power series, when I noticed that polynomials aren't evaluated as I would expect.
I created this minimal working example; the function s should evaluate for z=0 to a[0], however it return simply 0.
Is there something I messed up?

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The value of s in z=0 should be a[0], however it returns 0:

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Thanks for your help,

Sören

## Strange behaviour when using assume and ...

Maple 18

Hi guys,

I'm doing some heavy analytical calculations, as the calculations take hours to finish, I want to save the results, which is easily done, however when I load the saved results, it behaves differently, somehow I can no longer substitute the variables. I extracted the main problem into the following minimal working example.

Thanks for any useful insight,

Cheers, Sören

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Now we can't substitute n in x:

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## patmatch perfomance...

Maple 18

Hej guys,

in some of my Maple worksheets I'm using Maples fit-function to obtain a rational function fit to some data, as I'm interested in the zeros of enumerator and denominator, I chose my fit function accordingly. Afterwards I need to extract the results (mainly the zeros) and do some more calculation steps with them. When evaluating rational functions of high degree, I noticed that my way of extracting the results (I'm using patmatch) becomes increasingly slow up to the point where it takes a couple of minutes to extract 10 numbers.
E.g. the following minimal example (download link at the bottom) takes more than 20 minutes on my machine (Maple 18.01 Build ID 935137; Red Hat Version 6.6 running on system with an i5-3570, 8 GB of RAM). Additionally, the calculation requires an unreasonable amount of RAM.
I can work around the problem to some degree by extracting the leading coefficient beforehand, resulting in a substantial speed up, still I think that there might be some error in the code or my usage of patmatch.

Is there another way to extract these numbers in a similarly simple fashion?

Cheers,

Sören

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a pathmatch with 9 variables requires roughly 200 MB of memory and takes about 7 s to finish on an i5-3570 CPU:

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a pathmatch with 9 variables requires roughly 2.2 GB (!) of memory and takes about 20 min (!) to finish on an i5-3570 CPU:

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