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Re: Arrays with NaN values [message #41347 is a reply to message #41253]

Tue, 05 October 2004 09:13

Paul Van Delst[1]
Messages: 1157
Registered: April 2002

Senior Member

Mark Hadfield wrote:
> David Fanning wrote:
>
>>
>> I think I would try something like this:
>>
>> index = Where(Finite(image) EQ 0, count)
>> IF count NE 0 THEN image[index] = 0
>
>
> Note that the first line could *not* be replaced by the (apparently
> reasonable)
>
> index = Where(NOT Finite(image), count)
>
> because the NOT operator and the WHERE function do not play well
> together. The reasons are explained here:
>
> http://www.dfanning.com/code_tips/bitwiselogical.html
>
> In IDL 6.0 the logical not operator, "~" operator was introduced to
> avoid this problem,

Man, the C-loving types really did a number on IDL. RSI musta hired a boatload of CS grads
from the same school or something to implement the OO stuff. :o) [and, just in case
anyone is irony impaired, yes, I am kidding]

> so the following would work
>
> index = Where(~Finite(image), count)

I realise "~" is a complement operator but when I look at the code above, I think "where
the elements of IMAGE are *approximately* finite" ..... huh?

Gosh, I have that old'n'crusty feeling coming on again. Back to DF's blog for some
restorative therapy......

paulv

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[Message index]

		Re: Arrays with NaN values By: Mark Hadfield on Mon, 04 October 2004 16:58
		Re: Arrays with NaN values By: David Fanning on Mon, 04 October 2004 13:35
		Re: Arrays with NaN values By: julio on Mon, 04 October 2004 10:08
		Re: Arrays with NaN values By: David Fanning on Sun, 03 October 2004 22:22
		Re: Arrays with NaN values By: julio on Sun, 03 October 2004 13:36
		Re: Arrays with NaN values By: David Fanning on Sat, 02 October 2004 23:30
		Re: Arrays with NaN values By: Paul Van Delst[1] on Tue, 05 October 2004 09:13

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