title: What is wrong with my Fourier Transformation (Convolution) in MathNet.Numerics? - C#
body: <p>I am trying to do a simple Convolution between 2 audio files using the <code>MathNet.Numerics's</code> FFT (Fast Fourier Transformation), but I get some weird background sounds, after the IFFT.</p>
  
  <p>I tested if it's the Convolution or the Transformations, thats causing the problem, and I found out that the problem shows already in the FFT -> IFFT (Inverze FFT) conversion. </p>
  
  <p><strong>My code for a simple FFT and IFFT:</strong></p>
  
  <pre><code>float[] sound; //here are stored my samples
  
  Complex[] complexInput = new Complex[sound.Length];
  for (int i = 0; i &lt; complexInput.Length; i++)
  {
        Complex tmp = new Complex(sound[i],0);
        complexInput[i] = tmp;
   }
  
  MathNet.Numerics.IntegralTransforms.Fourier.Forward(complexInput);
  
  //do some stuff
  
  MathNet.Numerics.IntegralTransforms.Fourier.Inverse(complexInput);
  
  float[] outSamples = new float[complexInput.Length];
  
  for (int i = 0; i &lt; outSamples.Length; i++)
       outSamples[i] = (float)complexInput[i].Real;
  </code></pre>
  
  <p>After this, the <code>outSamples</code> are corrupted with some wierd background sound/noise, even though I'm not doing anything between the FFT and IFFT.</p>
  
  <p>What am I missing?</p>