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copied!<p>Many built-in operations like <a href="http://www.mathworks.com/help/matlab/ref/sum.html" rel="noreferrer"><code>sum</code></a> and <a href="http://www.mathworks.com/help/matlab/ref/prod.html" rel="noreferrer"><code>prod</code></a> are already able to operate across rows or columns, so you may be able to refactor the function you are applying to take advantage of this.</p> <p>If that's not a viable option, one way to do it is to collect the rows or columns into cells using <a href="http://www.mathworks.com/help/matlab/ref/mat2cell.html" rel="noreferrer"><code>mat2cell</code></a> or <a href="http://www.mathworks.com/help/matlab/ref/num2cell.html" rel="noreferrer"><code>num2cell</code></a>, then use <a href="http://www.mathworks.com/help/matlab/ref/cellfun.html" rel="noreferrer"><code>cellfun</code></a> to operate on the resulting cell array.</p> <p>As an example, let's say you want to sum the columns of a matrix <code>M</code>. You can do this simply using <a href="http://www.mathworks.com/help/matlab/ref/sum.html" rel="noreferrer"><code>sum</code></a>:</p> <pre><code>M = magic(10); %# A 10-by-10 matrix columnSums = sum(M, 1); %# A 1-by-10 vector of sums for each column </code></pre> <p>And here is how you would do this using the more complicated <a href="http://www.mathworks.com/help/matlab/ref/num2cell.html" rel="noreferrer"><code>num2cell</code></a>/<a href="http://www.mathworks.com/help/matlab/ref/cellfun.html" rel="noreferrer"><code>cellfun</code></a> option:</p> <pre><code>M = magic(10); %# A 10-by-10 matrix C = num2cell(M, 1); %# Collect the columns into cells columnSums = cellfun(@sum, C); %# A 1-by-10 vector of sums for each cell </code></pre>

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