Help/UGens/FFT/PV_Div.html

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  30 <p class="p1"><span class="s1"><b>PV_Div<span class="Apple-tab-span">   </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span></b></span><b>complex division</b></p>
  31 <p class="p2"><br></p>
  32 <p class="p3"><b>PV_Div(bufferA,<span class="Apple-converted-space">  </span>bufferB)</b></p>
  33 <p class="p2"><br></p>
  34 <p class="p3">Complex division.</p>
  35 <p class="p3"><b>bufferA</b> - fft buffer A.</p>
  36 <p class="p3"><b>bufferB</b> - fft buffer B.</p>
  37 <p class="p2"><br></p>
  38 <p class="p4"><span class="s2">See also <a href="PV_Mul.html"><span class="s3">PV_Mul</span></a>, <a href="PV_MagDiv.html"><span class="s3">PV_MagDiv</span></a>, <a href="FFT Overview.html"><span class="s4">FFT Overview</span></a>.</span></p>
  39 <p class="p2"><br></p>
  40 <p class="p5"><br></p>
  41 <p class="p3"><b>Example</b></p>
  42 <p class="p3">In this example we estimate the transfer function of the <a href="../Filters/LPF.html"><span class="s5">LPF</span></a> UGen. The transfer function is estimated by dividing the FFT of the output, by the FFT of the input, and looking at the magnitudes in the result.</p>
  43 <p class="p5"><br></p>
  44 <p class="p6">(</p>
  45 <p class="p6">s.waitForBoot {</p>
  46 <p class="p6"><span class="Apple-tab-span">     </span><span class="s6">var</span> fftsize = 16384;</p>
  47 <p class="p6"><span class="Apple-tab-span">     </span>b = <span class="s6">Buffer</span>.alloc(s, fftsize)</p>
  48 <p class="p6">}</p>
  49 <p class="p6">);</p>
  50 <p class="p5"><br></p>
  51 <p class="p5"><br></p>
  52 <p class="p6">(</p>
  53 <p class="p6">x = {</p>
  54 <p class="p7"><span class="s2"><span class="Apple-tab-span">    </span></span>// Any input should theoretically be OK, white noise is a good choice</p>
  55 <p class="p8"><span class="s2"><span class="Apple-tab-span">    </span></span>var<span class="s2"> son = </span>WhiteNoise<span class="s2">.ar;</span></p>
  56 <p class="p7">//<span class="Apple-tab-span">   </span>var son = Impulse.ar;</p>
  57 <p class="p6"><span class="Apple-tab-span">     </span><span class="s7">var</span> out = <span class="s7">LPF</span>.ar(son, <span class="s7">MouseX</span>.kr(100, 10000, 1));</p>
  58 <p class="p6"><span class="Apple-tab-span">     </span><span class="s7">var</span> fft1 = <span class="s7">FFT</span>(<span class="s7">LocalBuf</span>(b.numFrames), son, wintype: 1);</p>
  59 <p class="p6"><span class="Apple-tab-span">     </span><span class="s7">var</span> fft2 = <span class="s7">FFT</span>(b, out, wintype: 1);</p>
  60 <p class="p5"><span class="Apple-tab-span">     </span></p>
  61 <p class="p7"><span class="s2"><span class="Apple-tab-span">    </span></span>// As with most PV_ ugens, the result is *actually* stored in the first fft buf</p>
  62 <p class="p6"><span class="Apple-tab-span">     </span><span class="s7">var</span> result = <span class="s7">PV_Div</span>(fft2, fft1);</p>
  63 <p class="p5"><span class="Apple-tab-span">     </span></p>
  64 <p class="p6"><span class="Apple-tab-span">     </span><span class="s7">Out</span>.ar(0, out.dup * 0.1);</p>
  65 <p class="p6">}.play;</p>
  66 <p class="p6">)</p>
  67 <p class="p9"><br></p>
  68 <p class="p7">// Now we can grab the FFT buffer and peek at the magnitudes</p>
  69 <p class="p6">(</p>
  70 <p class="p6">w = <span class="s6">Window</span>.new.front;</p>
  71 <p class="p6">t = <span class="s6">Task</span>{loop{</p>
  72 <p class="p6"><span class="Apple-tab-span">     </span>0.1.wait;</p>
  73 <p class="p6"><span class="Apple-tab-span">     </span>b.loadToFloatArray(action: {<span class="s6">|data|</span> {</p>
  74 <p class="p6"><span class="Apple-tab-span">     </span><span class="Apple-tab-span">    </span>w.view.children.do(<span class="s6">_</span>.remove);</p>
  75 <p class="p6"><span class="Apple-tab-span">     </span><span class="Apple-tab-span">    </span>w.refresh;</p>
  76 <p class="p6"><span class="Apple-tab-span">     </span><span class="Apple-tab-span">    </span>data[2..].clump(2)</p>
  77 <p class="p6"><span class="Apple-tab-span">     </span><span class="Apple-tab-span">    </span>.collect {<span class="s6">|a|</span> (a[0].squared + a[1].squared)}</p>
  78 <p class="p6"><span class="Apple-tab-span">     </span><span class="Apple-tab-span">    </span>.collect {<span class="s6">|a|</span> if(a.isNaN){ 0.post }{ a } }</p>
  79 <p class="p6"><span class="Apple-tab-span">     </span><span class="Apple-tab-span">    </span>.plot(parent: w)</p>
  80 <p class="p6"><span class="Apple-tab-span">     </span>}.defer});</p>
  81 <p class="p6">}}.play;</p>
  82 <p class="p6">)</p>
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