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  <title>Basic math with AOs (LTPDA Toolbox)</title>
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  <h1 class="title"><a name="f3-12899" id="f3-12899"></a>Basic math with AOs</h1>
  <hr>

  <p>
	<p>
  Most of the basic math operations supported by MATLAB have been implemented
  as AO class methods. For example, suppose you want to add two AOs together, then you can do
</p>
<div class="fragment"><pre>
    a = ao(1);
    b = ao(2);
    c = a+b
    plot(c.hist)
</pre></div>
<p>
  <i>Note: the units of the two AOs for addition and subtraction must be the same. You can't
  add apples to oranges, but you can add dimensionless (empty units) to oranges.</i>
</p>
<p>
  Some of the standard operators can act as modifiers. For example, if you want to square an AO:
</p>
<div class="fragment"><pre>
    a = ao(2);
    a.^2
</pre></div>
<p>
  will do the job.
</p>
<p>
  The operators follow MATLAB rules whenever possible. So if you want to add
  a single AO to a vector of AOs, you can. However, if you want to add two
  vectors of AOs together, the two vectors must contain the same number of AOs.
  For example,
</p>
<div class="fragment"><pre>
    a = [ao(1) ao(2) ao(3)];
    b = ao(4);
    c = a + b
</pre></div>
<p>
  will work fine and result in <tt>b</tt> being added to each element of <tt>a</tt>. However,
</p>
<div class="fragment"><pre>
    a = [ao(1) ao(2) ao(3)];
    b = [ao(4) ao(5)];
    c = a + b
</pre></div>
<p>
  will give an error.
</p>
<p>
  You can do all of this on the workbench as well, of course.
</p>
<p>
  Try the following:
  <ol>
    <li>Start up the workbench, and/or open a new pipeline</li>
    <li>Drag an <tt>ao</tt> constructor block to the canvas</li>
    <li>Set the AO block to be constructed "From XY Values"</li>
    <li>Duplicate the block two more times (<tt>ctrl/cmd-d</tt>)</li>
    <li>Enter a number for the sampling ferquency <tt>fs</tt></li>
    <li>Enter a vector the same length for the <tt>y</tt> value of each block</li>
    <li>Drag a <tt>plus</tt> block to the canvas</li>
    <li>You'll see that by default the "plus" block has two inputs. To add another input,
    right-click on the block and choose "Add input" from the context menu</li>
    <li>Connect each AO block to the plus block. The easiest way to do that is to
      select the AO block (source) and then <tt>ctrl+left-click</tt>  (<tt>cmd+left-click</tt> on Mac systems) on the plus (destination) block. You
      can also drag a pipe from the output terminal of the AO blocks to the input terminals of the plus block
    if you want to be explicit about which input ports are used.</li>
    <li>Add an <tt>iplot</tt> block to the canvas and connect the output of the <tt>plus</tt> block to the input
      of the <tt>iplot</tt> block. You should now have a pipeline something like:<br>
      <img src="images/ltpda_training_1/topic1/ao_plus_eg.png" alt="AO plus example" border="1">
    </li>
    <li>Execute the pipeline and you should see a plot something like the one below, depending on what
      data values you gave to the <tt>ao</tt> constructors
    <img src="images/ltpda_training_1/topic1/ao_plus_plot.png" alt="AO plus plot" border="1"></li>
  </ol>
</p>


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      <td align="right">Saving and loading AOs</td>

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  <p class="copy">&copy;LTP Team</p>
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author	Daniele Nicolodi <nicolodi@science.unitn.it>
date	Wed, 07 Dec 2011 17:29:47 +0100
parents	f0afece42f48
children