help-octave
[Top][All Lists]

## Re: It is very difficult for Octave to calculate the inverse Laplace tra

 From: Colin Macdonald Subject: Re: It is very difficult for Octave to calculate the inverse Laplace transform of some functions Date: Mon, 6 Jan 2020 01:45:58 -0800 User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.3.1

```On 2020-01-06 12:28 a.m., billyandriam wrote:
```
```I had no intention to torture test Gnu Octave. I had this  Exercise from my
Circuit Analysis Textbook
<https://electronics.stackexchange.com/questions/474650/solving-a-linear-system-of-equations-from-a-mesh-analysis-in-the-s-domain/>
which I was trying to solve. It is about circuit Analysis and one has to
find Mesh currents from a planar circuit.
In the last step, one has to find the inverse Laplace transform of the two
functions.
I only found out that Gnu Octave takes a huge amount of time to calculate
the inverse Laplace transform of some functions. Yesterday night, I was
going to bed and started the calculation only to find out in the morning
that it was not yet done calculating.

Here is a screenshot:
<https://octave.1599824.n4.nabble.com/file/t373596/Annotation_2020-01-06_110927.png>

I got the job done using Wolfram Alpha but, that leaves me a big concern. I
don't know if I can rely on Octave's symbolic calculation abilities if I
happen to encounter a comparable question in my exam and if Octave stalls.
```
```
```
Octave's Symbolic package relies on Sympy. While it can do transforms, its perhaps not its strongest feature.
```
Some things you could try:

1.  Make sure you're running a recent version of Sympy (1.4 or 1.5)

```
2. Try to isolate the simplest problem for which it fails, then you or I can report it upstream at https://github.com/sympy/sympy/issues (For example, there are very large integers in the screenshot you provided: does it also fail for rational expressions of quadrics with smaller coefficients?)
```
best,
Colin

```

reply via email to