LOWESS Smoothing VI

[alukindo]

Hi:

Does anyone know of a fast algorithm for X,Y plot smoothing based on the LOWESS algorithm? There is one here

but I am looking for a faster implementation.

Thanks

Anthony

[Karissap]

Here's some tips from NI that might be helpful to improve the VI you found: improving VI execution speed

Otherwise, it is faster to write the algorithm in something like C, and call the dll in LabVIEW. See this thread

[Rolf Kalbermatter]

QUOTE(Karissap @ Jun 12 2007, 11:07 PM)

Otherwise, it is faster to write the algorithm in something like C, and call the dll in LabVIEW. See http://forums.lavag.org/index.php?showtopic=3291' target="_blank">this thread

This statement is wrong in more than one way.

First LabVIEW does not necessarily have to be significantly slower than C. It will never be faster provided you use comparable algorithmes but much slower is a statement that holds simply not true for many algorithmes.

I've done bitmap import and export back in ~94 completely in LabVIEW including supporting simple compression schemes such as RLE etc and the routines where actually faster than calling Windows 3.1 16 bit APIs for doing the same.

The problem in LabVIEW is almost always not that it is in itself slow but that it is so easy to come up with a terrible algorithme that usually seems to do what you want but with a bad performance. Doing the same in C you do need to have a good understanding of what you want to do, how you are going to do it and how the C compiler will deal with certain thngs in your code. All this is most often absent when I see someone implementing an algorithme in LabVIEW and complaining afterwards about its performance.

Also it is wrong in that writing an algortihme in C is never going to be faster than doing it in LabVIEW. It's runtime performance can be and does sometimes be significantly faster but the implementation is definitely a different thing. Of course assuming that you know both LabVIEW and C equelly well.

Rolf Kalbermatter

[crelf]

QUOTE(rolfk @ Jun 15 2007, 06:20 PM)

First LabVIEW does not necessarily have to be significantly slower than C.

Well said Rolf