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Topic: Matrix dimensions must agree.
Replies: 13   Last Post: Mar 24, 2014 5:34 PM

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dpb

Posts: 8,259
Registered: 6/7/07
Re: Matrix dimensions must agree.
Posted: Mar 21, 2014 11:40 AM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

On 3/21/2014 8:46 AM, Steven Lord wrote:
> "Vitor Andrade" <vitor.luiz.de.andrade@gmail.com> wrote in message
> news:lghenc$13g$1@newscl01ah.mathworks.com...

...
>>> dpb <none@non.net> wrote in message <lgfaqk$820$1@speranza.aioe.org>...
>>> > On 3/20/2014 12:57 PM, Vitor Andrade wrote:
>
...

>>>> if x > y
a(y+1:end,:)=[];
...
>> elseif y > x
b(x+1:end,:)=[];
end
...

>
> I wouldn't use this approach; I'd instead select the elements to keep.
> It avoids the IF and ELSEIF statements at the expense of a call to MIN:
>
> minRows = min(x, y);
> a = a(1:minRows, :);
> b = b(1:minRows, :);
>

...

It then also has the cost of the selection on both where one is already
ok that the if...elseif avoids which is why I went that route.

My _real_ suggestion/hope was that Vitor would rethink his generation
process and avoid the problem at the start instead of having to fix it
up afterwards.

I also wrote the example for vectors illustrating the idea (hence
length() and linear addressing) but I suppose expecting the
extrapolation to an array was too much of leap of faith for the neophyte :)

--




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