Real Fast Fourier transform
Compute a real Fast Fourier transform of x.
rfft(x)
x |
The vector whose Fourier transform you wish to take |
Given a vector x this function computes the real continuous Fourier
transform of x, i.e. it regards x as points on a periodic
function on [0,1] starting at 0, and finding the coefficients of the functions
1,
sqrt(2) cos(2 pi t),
sqrt(2) sin(2 pi t), etc. that gives the expansion
of the interpolant of x. The number of terms in the expansion
is the length of x. If x is of even length, the last
coefficient will be that of a cosine term with no matching sine.
Returns the Fourier coefficients
Bernard Silverman
x <- seq(from=0, to=2*pi, length=150) s1 <- sin(10*x) s2 <- sin(7*x) s <- s1 + s2 w <- rfft(s) ## Not run: ts.plot(w) # # Should see two peaks, corresponding to the two sines at different frequencies #
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