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1D array problem for butterworth.pro [message #92534]

Tue, 05 January 2016 23:18

kagoldberg
Messages: 26
Registered: November 2012

Junior Member

I stumbled across a major problem with calculating 1D butter worth filters in IDL 8.5. (This bug was not in IDL 8.3. I don't know about 8.4.)

When you ask for 1D output, butterworth.pro extracts a 1D vector from the dist(x) function, which is a 2 dimensional, square array. As you might guess, as the array size gets large, IDL has to calculate a 2D dist() result with N^2 points! IDL 8.3 did not do this.

It brought my computer to its knees a few times before I was able to isolate it, and replace the built-in butterworth.pro with my own kludge.

Instead of (dist(x))[*,0], they should have used dist(x,1) and... problem solved.

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[Message index]

		1D array problem for butterworth.pro By: kagoldberg on Tue, 05 January 2016 23:18
		Re: 1D array problem for butterworth.pro By: chris_torrence@NOSPAM on Wed, 06 January 2016 09:42
		Re: 1D array problem for butterworth.pro By: Ken G on Mon, 11 January 2016 09:10

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