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README.md

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+# SwiftPFFFT
+
+Swift package providing a PFFFT (Pretty Fast, Fast Fourier Transform) library with wrapper.
+
+This code is based on the marton78 fork of PFFFT that was forked from the original PFFFT implementation
+by Julien Pommier. This fork provides support for doubles in addition to floats and provides additional SIMD implementations:
+
+The origin for the C implementation in this package is https://github.com/marton78/pffft.
+
+PFFFT provides substantial performance improvement over KissFFT. The advantage over FFTW is reasonable
+performance with much simpler usage and a permissive 3 clause BSD license.
+
+## Example
+
+``` swift
+
+// construct an interface for FFT, IFFT and convolutions. The interface is parameterized on the
+// type of element in the signal (time) domain. The spectrum (frequency) domain type will always be
+// complex. For a real valued signal the spectrum size will be `n / 2`, with the packing convention
+// 
+let fft = try FFT<Complex<Float>>(n: 16)
+let signal = fft.makeSignalBuffer()
+
+signal.mutateEach { (i, v) in
+    v = Complex(Float(i) + 1.0, Float(i) - 2.0)
+}
+
+let spectrum = fft.makeSpectrumBuffer()
+fft.forward(signal: signal, spectrum: spectrum)
+
+fft.inverse(spectrum: spectrum, signal: signal)
+
+```