What happens in the VI "Undecimated Wavelet Transform"

[Thomasschoenau]

Hello,

i wrote a LabView programm using the VI "Undecimated Wavelet Transform" from the wavelet-ttolbox.

Now, I want to translate parts of the programm into MatLab and must see that the MatLab-code creates different results. The MatLab functions that I used as replacement for "Undecimated Wavelet Transform" are "swt" and "ndwt". Both create results that look quite similiar to the LabView-results, but some details differ (for example there are less spikes in the LabView-result).

Furthermore, the MatLab-function "ndwt" increasesthe length of the array from 10000 to 10018 samples. This continuation is done to avoid problems at the border of the array.

I analyzed the "Undecimated Wavelet Transform"-VI and found, that it also increases the array length internally by periodic continuation. However, the resulting array of "Undecimated Wavelet Transform" remains the size of the input array.

So finally, I would like to know what happens in "Undecimated Wavelet Transform" and how I could reproduce this behaviour in other programming languages (for example im MatLab).

Thanks a lot

Thomas

[TinchoL]

Hello Thomas!
I took a look at your post. Your question is very broad. Could you be more specific about your concern?

As you mentioned, you can take a look inside the VIs that performs the Undecimated Wavelet Transform and see all the steps and functions that are used.
I took a look inside myself. And you will get more out of it, if you do that too, as if I try to debug the whole VI and write some pages explaining it.

And as you also wrote, MatLab offers similar functions and the MatLab Help search engine provides examples to use them.
If the results you expect, are not exactly the same, you could program a function in MatLab using the LabView VI as a guide. The advantage of LabVIEW is that you can follow the programs flow step by step with the HIGHLIGHT option. So if you need to create a code in MatLab or C++ or any other language, you could copy the sequence of LabVIEW.

Best Regards.