From help-request at octave dot org Fri Jun 18 13:34:03 2004
Subject: Re: no way for simple matrix lookup ?
From: Julius Smith <jos at ccrma dot stanford dot edu>
To: "D. Goel" <deego at gnufans dot org>
Cc: help at octave dot org
Date: Fri, 18 Jun 2004 11:35:42 -0700

Oops - I meant diag(A(b',c)) of course -- jos

At 11:30 AM 6/18/2004, Julius Smith wrote:
>How about A(diag(b',c)) ?
>
>-- jos
>
>At 10:33 AM 6/16/2004, D. Goel wrote:
>
>>Mike, that doesn't work, your recipe below is the first thing I tried.
>>
>>Example, A = [1 3; 2 4]
>>b=c=[1 2].
>>
>>The answer needed is [1 4], but both of your answers below give me [1
>>2 3 4].
>>
>>
>>Mike Miller <mbmiller at taxa dot epi dot umn dot edu> writes:
>>
>>
>> > D = A(b,c)
>> >
>> > And your variable D will be a matrix with size(D)=[length(b),
>> > length(c)]. You can transform it into a vector using D=D(:), or you
>> > can do this:
>> >
>> > D = reshape(A(b, c), length(b)*length(c), 1)
>> >
>> > You don't have to loop over 'i'.
>> >
>> > Best,
>> >
>> > Mike
>> >
>> >
>> >
>>[...]
>>
>>
>>
>>
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>>
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>_____________________________
>Julius O. Smith III <jos at ccrma dot stanford dot edu>
>Assoc. Prof. of Music and (by courtesy) Electrical Engineering
>CCRMA, Stanford University
>http://www-ccrma.stanford.edu/~jos/
>
>
>
>-------------------------------------------------------------
>Octave is freely available under the terms of the GNU GPL.
>
>Octave's home on the web:  http://www.octave.org
>How to fund new projects:  http://www.octave.org/funding.html
>Subscription information:  http://www.octave.org/archive.html
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_____________________________
Julius O. Smith III <jos at ccrma dot stanford dot edu>
Assoc. Prof. of Music and (by courtesy) Electrical Engineering
CCRMA, Stanford University
http://www-ccrma.stanford.edu/~jos/



-------------------------------------------------------------
Octave is freely available under the terms of the GNU GPL.

Octave's home on the web:  http://www.octave.org
How to fund new projects:  http://www.octave.org/funding.html
Subscription information:  http://www.octave.org/archive.html
-------------------------------------------------------------