Add FFT latex notes (incomplete)

fft-notes.bib

@@ -0,0 +1,20 @@
+@misc{gstrang,
+	title = {Linear Algebra and Its Applications, by Gilbert Strang (chapter 3.5)},
+	howpublished = "\url{https://archive.org/details/linearalgebrait00stra}",
+}
+@misc{tpornin,
+	title = {{Thomas Pornin} mathoverflow answer},
+	howpublished = "\url{https://crypto.stackexchange.com/a/63616}",
+}
+@misc{rfateman,
+	title = {notes by {Prof. R. Fateman}},
+	howpublished = "\url{https://www.csee.umbc.edu/~phatak/691a/fft-lnotes/fftnotes.pdf}",
+}
+@misc{fftrs,
+	title = {fft-rs},
+	howpublished = "\url{https://github.com/arnaucube/fft-rs}",
+}
+@misc{fftsage,
+	title = {fft-sage},
+	howpublished = "\url{https://github.com/arnaucube/math/blob/master/fft.sage}",
+}