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#ifndef CALCULATE_FFT_SIZE_H
#define CALCULATE_FFT_SIZE_H
namespace wsclean {
namespace detail {
inline bool hasLowPrimeFactors(size_t number) {
while (number > 7) {
if (number % 2 == 0)
number /= 2;
else if (number % 3 == 0)
number /= 3;
else if (number % 5 == 0)
number /= 5;
else if (number % 7 == 0)
number /= 7;
else
return false;
}
return true;
}
} // namespace detail
inline void CalculateFFTSize(size_t size, double pixelScale, double beamSize,
size_t& minimalSize, size_t& optimalSize) {
double totalSize = double(size) * pixelScale;
// Calc min res based on Nyquist sampling rate
minimalSize = size_t(ceil(totalSize * 2 / beamSize));
optimalSize = minimalSize;
if (optimalSize % 4 != 0) optimalSize += 4 - (optimalSize % 4);
while (!detail::hasLowPrimeFactors(optimalSize) && optimalSize < size)
optimalSize += 4;
if (optimalSize > size) optimalSize = size;
}
} // namespace wsclean
#endif
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