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POfftwpp creates a zero filled array after a convolution
 

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  1. POfftwpp creates a zero filled array after a convolution
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    <p>I use fftwpp to transform both my data and my convolution kernel into the fourier space, multiply them together like in a scalar product and convert them back to the real space. When I first run the program, it creates an array which is completely filled with zeros. When I run it again, it gives me the desired results.</p> <p>While running it, a <code>wisdom3.txt</code> is created. If I delete it, the program takes a lot of time to create a zero filled array again.</p> <p>What is wrong with my code?</p> <pre><code>// sx, sy and sz are the dimensions of my data int szp = sz / 2 + 1; size_t align = sizeof(Complex); // creates arrays to store the data in, the double one is for the real data // the Complex one for the fourier data array3&lt;double&gt; f(sx, sy, sz, align); array3&lt;Complex&gt; g(sx, sy, szp, align); // copying data into double array for(int k = 0; k &lt; sz; k++) for(int j = 0; j &lt; sy; j++) for(int i = 0; i &lt; sx; i++) f(i, j, k) = data[i + sx * j + sx * sy * k]; // transforming data into fourier space rcfft3d Forward3(sz, f, g); Forward3.fft(f, g); // generate the kernel array3&lt;double&gt; kernel(sx, sy, sz); array3&lt;Complex&gt; kernel2(sx, sy, szp, align); // more code to create the kernel left out ... // transform the kernel into the fourier space rcfft3d ForwardKernel3(sz, kernel, kernel2); ForwardKernel3.fft(kernel, kernel2); // multiplying data and kernel in fourier space together for(int k = 0; k &lt; szp; k++) for(int j = 0; j &lt; sy; j++) for(int i = 0; i &lt; sx; i++) g(i, j, k) = g(i, j, k) * kernel2(i, j, k); // transform back to normal space crfft3d Backward3(sz, g, f); Backward3.fftNormalized(g, f); // putting everything in the results array and normalize for(int k = 0; k &lt; sz; k++) for(int j = 0; j &lt; sy; j++) for(int i = 0; i &lt; sx; i++) result[i + sx * j + sx * sy * k] = (f(i, j, k) &gt;= thresholdValue ? f(i, j, k) : 0); </code></pre>
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