without a for loop? (was "compiling .m files")

[Mike Miller]

On Wed, 13 Nov 2002, Hein Zelle wrote:

> Unrelated question: is there a way to do the following without using a
> for loop?
>
> a = [1, 2; 3, 4];
> b = mean(a);
>
> for r = 1:2
>   anomaly(r,:) = a(r,:) - b
> endfor
>
> I would like to use the : notation to indicate that I want the row
> vector b to be subtracted from each row of a, but i can't figure out how
> to do it.


How about this?:

anomaly = a - ones(size(a,1),1)*b ;

In general, you could do this for any matrix X:

Y = X - ones(size(X,1),1) * mean(X)

Then mean(Y) = zeros(1,size(X,2)), always.

Mike



-------------------------------------------------------------
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
-------------------------------------------------------------