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Previous: <a rel="previous" accesskey="p" href="Miscellaneous-Techniques.html#Miscellaneous-Techniques">Miscellaneous Techniques</a>,
Up: <a rel="up" accesskey="u" href="Vectorization-and-Faster-Code-Execution.html#Vectorization-and-Faster-Code-Execution">Vectorization and Faster Code Execution</a>
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<h3 class="section">19.6 Examples</h3>
<p>The following are examples of vectorization questions asked by actual
users of Octave and their solutions.
<!-- FIXME: We need a lot more examples here. -->
<ul>
<li>For a vector <code>A</code>, the following loop
<pre class="example"> n = length (A);
B = zeros (n, 2);
for i = 1:length(A)
## this will be two columns, the first is the difference and
## the second the mean of the two elements used for the diff.
B(i,:) = [A(i+1)-A(i), (A(i+1) + A(i))/2)];
endfor
</pre>
<p class="noindent">can be turned into the following one-liner:
<pre class="example"> B = [diff(A)(:), 0.5*(A(1:end-1)+A(2:end))(:)]
</pre>
<p>Note the usage of colon indexing to flatten an intermediate result into
a column vector. This is a common vectorization trick.
</ul>
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