comp.lang.idl-pvwave archive: archive » FFT with NANs in an array

Home » Public Forums » archive » FFT with NANs in an array

Show: Today's Messages :: Show Polls :: Message Navigator
E-mail to friend

Re: FFT with NANs in an array [message #49436 is a reply to message #49342]

Thu, 20 July 2006 17:08

adisn123
Messages: 44
Registered: July 2006

Member

^^;
Thanks for the tip.

Steve Eddins wrote:
> Steve Eddins wrote:
>> adisn123@yahoo.com wrote:
>>> Hi,
>>>
>>> I'm trying to fourier transform a spacial domain image to frequency
>>> domain using FFT function in IDL.
>>>
>>> My image has quite a bit of NANs in an array, about 5%.
>>>
>>> When I use FFT into the image, it doesn't give me any errors, but when
>>> I inversely fourier transform after
>>>
>>> filtering, it gives a little funky result.
>>
>> I would have expected you to get a VERY funky result. Since every
>> output element of an FFT depends on every input element, I'd expect
>> every output element of your result to be NaN.
>>
>>> How do I make FFT ignore NANs in their job or filtering?
>>
>> I think you'll need to explicitly replace the NaNs with 0s, like this:
>>
>> A(isnan(A)) = 0;
>
> Whoops, forgot which newsgroup I was in, sorry. The above code line is
> MATLAB syntax. Replace it with suitable IDL syntax.
>
> --
> Steve Eddins
> http://blogs.mathworks.com/steve

Report message to a moderator

[Message index]

		FFT with NANs in an array By: adisn123 on Thu, 20 July 2006 11:00
		Re: FFT with NANs in an array By: Kenneth P. Bowman on Thu, 20 July 2006 19:48
		Re: FFT with NANs in an array By: adisn123 on Thu, 20 July 2006 17:08
		Re: FFT with NANs in an array By: Steve Eddins on Thu, 20 July 2006 12:44
		Re: FFT with NANs in an array By: Steve Eddins on Thu, 20 July 2006 12:42
		Re: FFT with NANs in an array By: Kenneth P. Bowman on Thu, 20 July 2006 12:24
		Re: FFT with NANs in an array By: R on Wed, 26 July 2006 15:47

Previous Topic:	Re: IDLgrPolygon with different colors for shading and lines
Next Topic:	Re: IDL_IDLBridge in Virtual Machine

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

] [

]

Current Time: Fri Oct 10 04:35:53 PDT 2025

Total time taken to generate the page: 1.04241 seconds