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Fast Fourier transform: Difference between revisions
added Ursala
(Since there's already a more efficient FFT built in, I didn't reinvent the wheel.) |
(added Ursala) |
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Line 330:
fft2: 0.000 0.000 0.000 8.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 8.000 0.000 0.000
</pre>
=={{header|Ursala}}==
The [http://www.fftw.org <code>fftw</code> library] is callable from Ursala using the syntax <code>..u_fw_dft</code> for a one dimensional forward discrete Fourier transform operating on a list of complex numbers. Ordinarily the results are scaled so that the forward and reverse transforms are inverses of each other, but additional scaling can be performed as shown below to conform to convention.
<lang ursala>#import nat
#import flo
f = <1+0j,1+0j,1+0j,1+0j,0+0j,0+0j,0+0j,0+0j> # complex sequence of 4 1's and 4 0's
g = c..mul^*D(sqrt+ float+ length,..u_fw_dft) f # its fft
#cast %jLW
t = (f,g)</lang>
output:
<pre>(
<
1.000e+00+0.000e+00j,
1.000e+00+0.000e+00j,
1.000e+00+0.000e+00j,
1.000e+00+0.000e+00j,
0.000e+00+0.000e+00j,
0.000e+00+0.000e+00j,
0.000e+00+0.000e+00j,
0.000e+00+0.000e+00j>,
<
4.000e+00+0.000e+00j,
1.000e+00-2.414e+00j,
0.000e+00+0.000e+00j,
1.000e+00-4.142e-01j,
0.000e+00+0.000e+00j,
1.000e+00+4.142e-01j,
0.000e+00+0.000e+00j,
1.000e+00+2.414e+00j>)</pre>
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