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Re: endless loop problem [message #68959 is a reply to message #68953]

Sun, 06 December 2009 17:20

Wasit.Weather
Messages: 62
Registered: February 2008

Member

On Dec 6, 5:52 pm, David Fanning <n...@dfanning.com> wrote:
> pp writes:
>
> .
>
>> L does not change because you are calculating the same thing over and
>> over again. L only depends on EC[0] and EC[1], and neither changes
>> when you go through the loop. So if L does not happen to be
>> <1.2840277, the loop will never end.
>
> And it is not likely that it will *ever* be 1.2840277!
>
> http://www.dfanning.com//math_tips/sky_is_falling.html
>
> 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.")

I should have given more explanations on this. L changes over each
iteration. There is no problem. I missed one letter, here is the
corrected one.
;E1 = Unit vector, known
; Z is known matrix
REPEAT BEGIN
EC = Z##E1
L = sqrt(EC[0]+EC[1])
E1 = EC/L
print,L
;Keep going until nothing is moved.
ENDREP UNTIL L LT 1.2840277

I am struggling to find eigenvalues and eigenvectors manually, instead
of IDL routines.

I think it might be a problem as David pointed out. But there should
be a value less than or greater than that value, right?
Thanks

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[Message index]

		Re: endless loop problem By: penteado on Sun, 06 December 2009 18:21
		Re: endless loop problem By: Wasit.Weather on Sun, 06 December 2009 17:20
		Re: endless loop problem By: David Fanning on Sun, 06 December 2009 15:52
		Re: endless loop problem By: penteado on Sun, 06 December 2009 15:28

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