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<h2>
<span class="refentrytitle">fft</span>
</h2>
<p>fft —
Complex-to-complex Fast Fourier Transform.
</p>
</div>
<div class="refsect1">
<a id="idm281472937519288"></a>
<h2>Description</h2>
<p>
Applies a forward Fast Fourier Transform to a complex-valued input 1-dimensional array producing a complex-valued output.
The output is another array containing the complex-valued signal, and both arrays are arranged in interleaved real-imaginary format.
The output array will have the same size as the input, and the transform size will be equivalent to half of the length of the array.
Non-power-of-two transforms are limited to even sizes with not too many factors.
</p>
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<div class="refsect1">
<a id="idm281472937517608"></a>
<h2>Syntax</h2>
<pre class="synopsis">kout[] <span class="command"><strong>fft</strong></span> kin[]</pre>
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<div class="refsect1">
<a id="idm281472937459320"></a>
<h2>Performance</h2>
<p>
<span class="emphasis"><em>kout[]</em></span> -- output array containing the complex-valued output. It will be created if it does not exist.
</p>
<p>
<span class="emphasis"><em>kin[]</em></span> -- input array containing the complex-valued input.
</p>
</div>
<div class="refsect1">
<a id="idm281472937456792"></a>
<h2>Examples</h2>
<p>
Here is an example of the fft opcode. It uses the file <a class="ulink" href="examples/fft.csd" target="_top"><em class="citetitle">fft.csd</em></a>.</p>
<div class="example">
<a id="idm281472937454840"></a>
<p class="title">
<strong>Example 276. Example of the fft opcode.</strong>
</p>
<div class="example-contents">
<p>See the sections <a class="link" href="UsingRealTime.html" title="Real-Time Audio"><em class="citetitle">Real-time Audio</em></a> and <a class="link" href="CommandFlags.html" title="Csound command line"><em class="citetitle">Command Line Flags</em></a> for more information on using command line flags.</p>
<div class="refsect1">
<a id="idm281472769676040"></a>
<pre class="programlisting">
<span class="nt"><CsoundSynthesizer></span>
<span class="nt"><CsOptions></span>
-d -o dac
<span class="nt"></CsOptions></span>
<span class="nt"><CsInstruments></span>
<span class="vg">ksmps</span> <span class="o">=</span> <span class="mi">64</span>
<span class="kd">instr</span> <span class="nf">1</span>
i<span class="n">fftsize</span> <span class="o">=</span> <span class="mi">1024</span>
k<span class="n">cnt</span> <span class="nb">init</span> <span class="mi">0</span>
k<span class="n">In</span><span class="p">[]</span> <span class="nb">init</span> i<span class="n">fftsize</span>
k<span class="n">Out</span><span class="p">[]</span> <span class="nb">init</span> i<span class="n">fftsize</span>
a<span class="n">1</span> <span class="nb">oscili</span> <span class="vg">0dbfs</span><span class="o">/</span><span class="mi">2</span><span class="p">,</span> <span class="mi">440</span>
<span class="k">if</span> k<span class="n">cnt</span> <span class="o">>=</span> i<span class="n">fftsize</span> <span class="k">then</span>
k<span class="n">Cmplx</span><span class="p">[]</span> <span class="nb">r2c</span> k<span class="n">In</span>
k<span class="n">Spec</span><span class="p">[]</span> <span class="nb">fft</span> k<span class="n">Cmplx</span>
k<span class="n">Cmplx</span> <span class="nb">fftinv</span> k<span class="n">Spec</span>
k<span class="n">Out</span> <span class="nb">c2r</span> k<span class="n">Cmplx</span>
k<span class="n">cnt</span> <span class="o">=</span> <span class="mi">0</span>
<span class="k">endif</span>
k<span class="n">In</span><span class="p">[]</span> <span class="nb">shiftin</span> a<span class="n">1</span>
a<span class="n">2</span> <span class="nb">shiftout</span> k<span class="n">Out</span>
k<span class="n">cnt</span> <span class="o">+=</span> <span class="vg">ksmps</span>
<span class="nb">out</span> a<span class="n">2</span>
<span class="kd">endin</span>
<span class="nt"></CsInstruments></span>
<span class="nt"><CsScore></span>
<span class="nb">i</span><span class="mi">1</span> <span class="mi">0</span> <span class="mi">10</span>
<span class="nt"></CsScore></span>
<span class="nt"></CsoundSynthesizer></span>
</pre>
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<br class="example-break" />
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<div class="refsect1">
<a id="idm281472937450776"></a>
<h2>See Also</h2>
<p>
<a class="link" href="vectorial.html" title="Vectorial Opcodes"><em class="citetitle"></em>Vectorial opcodes</a>,
<a class="link" href="arrayOpcodes.html" title="Array Opcodes"><em class="citetitle"></em>array opcodes</a>
</p>
</div>
<div class="refsect1">
<a id="idm281472937447768"></a>
<h2>Credits</h2>
<p>
</p>
<table border="0" summary="Simple list" class="simplelist">
<tr>
<td>Author: Victor Lazzarini</td>
</tr>
<tr>
<td>NUI Maynooth</td>
</tr>
<tr>
<td>2014</td>
</tr>
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<p>
</p>
<p>New in version 6.04</p>
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