Ooura FFT front-end for Ruby
This is a Ruby's front end that allows to use FFT software of Professor Ooura (Kyoto University).
After downloading, unzip it to any directory, go to the lib directory, and type the following in the terminal to import it.
$ ruby extconf.rb
$ make
$ make install
$ make distclean
It is used as follows:
def sinewave(a, f0, n, fs)
a * Math.sin(2.0 * Math::PI * f0 * n / fs)
end
a = 0.1
f0 = 500.0
fs = 8000
ary = Array.new(8){|n| sinewave(a, f0, n, fs)}
# =>
# [0.0,
# 0.03826834323650898,
# 0.07071067811865475,
# 0.09238795325112868,
# 0.1,
# 0.0923879532511287,
# 0.07071067811865477,
# 0.03826834323650899,
# 1.2246467991473533e-17,
# -0.03826834323650893,
# -0.07071067811865471,
# -0.09238795325112865,
# -0.1,
# -0.0923879532511287,
# -0.07071067811865477,
# -0.038268343236509045]
fft = FFT.cdft(ary)
# =>
# [(8.163540703054581e-17+0.0i),
# (-1.960250254624452e-16+0.8i),
# (-7.379687742073657e-18+1.3976414209117932e-16i),
# (4.663199920916804e-17+1.3877787807814457e-17i),
# (-2.938689543196984e-17+8.326672684688674e-17i),
# (4.663199920916804e-17+1.3877787807814457e-17i),
# (3.187262372502072e-17+5.649741524429257e-17i),
# (5.377515507821501e-17+0.0i),
# (2.6124255799287986e-17+0.0i),
# (5.377515507821501e-17+0.0i),
# (3.187262372502072e-17-5.649741524429257e-17i),
# (4.663199920916804e-17-1.3877787807814457e-17i),
# (-2.938689543196984e-17-8.326672684688674e-17i),
# (4.663199920916804e-17-1.3877787807814457e-17i),
# (-7.379687742073657e-18-1.3976414209117932e-16i),
# (-1.960250254624452e-16-0.8i)]
FFT.cdft(fft, inversion: true)
# =>
# [(1.232595164407831e-32+0.0i),
# (0.6122934917841437+0.0i),
# (1.131370849898476+0.0i),
# (1.478207252018059+0.0i),
# (1.6+0.0i),
# (1.4782072520180591+0.0i),
# (1.1313708498984765+0.0i),
# (0.6122934917841438+0.0i),
# (1.9594348786357647e-16+0.0i),
# (-0.6122934917841428+0.0i),
# (-1.1313708498984756+0.0i),
# (-1.4782072520180585+0.0i),
# (-1.6+0.0i),
# (-1.4782072520180591+0.0i),
# (-1.1313708498984765+0.0i),
# (-0.6122934917841447+0.0i)]