Differences
This shows you the differences between two versions of the page.
Both sides previous revisionPrevious revisionNext revision | Previous revisionNext revisionBoth sides next revision | ||
time_series:fft [2014/08/11 21:12] – phreazer | time_series:fft [2014/08/11 21:25] – phreazer | ||
---|---|---|---|
Line 4: | Line 4: | ||
$e^-i\dots$ | $e^-i\dots$ | ||
- | $e^-x = \cos x - i sin \x$ | + | |
+ | Komplexe Exponentialfunktion: | ||
+ | $e^{-x} = \cos x - i \sin x$ | ||
+ | |||
+ | $X[k] = \sum^{N-1}_{n=0} X[n] \cos(\omega_k * n) - i \sum^{N-1}_{n=0} X[n] \sin(\omega_k * n)$ | ||
+ | |||
+ | $\omega_k= \frac{2 \pi k}{N}$ | ||
+ | |||
+ | Multiplikation und Summierung => Korrelation | ||
+ | |||
+ | Maß für Anwesendheit von Cosinus (Reelle Zahlen) / Sinus Wellen (Imaginäre Zahlen) | ||
+ | |||
+ | k => Anzahl der Zyklen. | ||