Inverse Laplace Transform?

[PolymerTim3]

Is there an inverse laplace transform available in LabView 8.20?  It looks like this question hasn't been asked in a couple years.  If not available, is there a reason why it hasn't been added? 

[Doug M]

PolymerTim,

There is not an Inverse Laplace Transform VI in LabVIEW 8.20.  I'll see if I can find out anything more...

[PolymerTim3]

Any new thoughts on this?

[Doug M]

PolymerTim,

I did ask our developer about this and this was part of his response:

" [the] Inverse Laplace transform needs to specify the contour of the integral since the integrand X(s) is a function of complex variable s. This is hard to implement...[the] [inverse??] Laplace transform is more suitable to represent a continuous system, not discrete system. To me, it should be in symbolic math field."

He also mentioned he had not heard of customers requesting this VI.  If you feel such a function would be of use to you I would strongly encourage you to leave product feedback on our website as this feedback is used to determine future features.  Hope this answers your question!

Message Edited by Doug M on 01-31-2007 10:42 AM

[PolymerTim3]

Thanks for the response.  I had a feeling it would be something like this.  Unfortunately, I don't have a very strong math background, but I am working on a new characterization technique where the analysis can take any of several routes.  One of the routes we were looking at uses an inverse Laplace, but as I review the literature deeper, it appears that this method contains a high degree of error.  I think this is for just the reason your developer mentioned, considering the analysis only involves about 100 points that are usually fit to a theoretical eqn for the inverse laplace function.  We will probably end up using one of the other analysis routes that has less error.

In case anyone is interested, the application is an analysis of the thermal fluctuations (Brownian motion) of micron-scale particles in a liquid medium.  By analyzing the trajectories of the particles with time rheological information such as viscosity of the medium can be obtained by a purely passive optical method.

Thanks again,
Tim

[AutoMeasure]

I wrote a Pulse Response Examiner VI that uses the Complex FFT to do a fast inverse Laplace transform.  The VI is posted at http://forums.lavag.org/t10263.html .  You need the Labview 8.5 full development system to run it.

The method I used has its limitations.  I would like to see a robust Inverse Laplace VI included with Labview.

[Neil.Pate]

Your demo VI is great, even if we forget the maths and just use it to teach RLC circuits!

[SolarAl]

Is there a way to download this example VI now?  Can't seem to find it on lavaorg...

[Peñata]

Hi SolarAl,

Unfortunately, if the example is no longer on lavaorg, you may be out of luck. I would suggest posting on that forum as well to see if anyone there still has it. Hopefully someone has a copy of it hanging around somewhere that they can get to you.

Thank you for choosing National Instruments.

Aaron Pena

National Instruments

Applications Engineer

http://www.ni.com/support

[SolarAl]

Thank you for the good idea