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Re: operator fails? [message #72600 is a reply to message #72599]

Thu, 23 September 2010 06:28

penteado
Messages: 866
Registered: February 2018

Senior Member
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On Sep 23, 10:20 am, Gray <grayliketheco...@gmail.com> wrote:
> On Sep 22, 8:13 pm, Gray <grayliketheco...@gmail.com> wrote:
>
>
>
>
>
>> On Sep 22, 4:59 pm, David Fanning <n...@dfanning.com> wrote:
>
>>> Gray writes:
>>>> Can anyone explain this?
>
>>>> IDL> nsrc = n_elements(srcy)
>>>> IDL> s = size(img,/dim)
>>>> IDL> bs = rebin([-10,10],2,nsrc,/sample)
>>>> IDL> yb = 0. > rebin(transpose(srcy),2,nsrc,/sample)+bs < s[1]-1
>>>> IDL> print, n_elements(where(yb lt 0))
>>>> 5
>
>>>> How does yb ever become less than 0? Isn't the > operator in this
>>>> usage supposed to prevent this?? Thanks.
>
>>> This is one of the classic gotchas. You are going
>>> to need some parentheses in that long line. Do you
>>> see it? :-)
>
>>> Cheers,
>
>>> David
>
>>> --
>>> David Fanning, Ph.D.
>>> Fanning Software Consulting, Inc.
>>> Coyote's Guide to IDL Programming:http://www.dfanning.com/
>>> Sepore ma de ni thui. ("Perhaps thou speakest truth.")
>
>> Oh. Oh, oh, oh. Grrrrrr..... >:O
>
> IDL> yb = 0 > (rebin(transpose(srcy),2,nsrc,/sample)+bs) < s[1]-1
> IDL> print, where(yb[0,*] le 0)
> 6 7 18 23 29
>
> Even with the parentheses it still doesn't work.

Did you not want it to be

yb = 0 > (rebin(transpose(srcy),2,nsrc,/sample)+bs) < (s[1]-1)

?

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[Message index]

		Re: operator fails? By: David Fanning on Thu, 23 September 2010 06:51
		Re: operator fails? By: Gray on Thu, 23 September 2010 06:41
		Re: operator fails? By: penteado on Thu, 23 September 2010 06:28
		Re: operator fails? By: Gray on Thu, 23 September 2010 06:20
		Re: operator fails? By: Gray on Wed, 22 September 2010 17:13
		Re: operator fails? By: David Fanning on Wed, 22 September 2010 13:59

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