Drop-in replacements for stats::fft() and stats::mvfft()

fft_stats() and mvfft_stats() take the same arguments, check them the same way and return the same structure as stats::fft() and stats::mvfft(): the attributes of z are kept, the inverse is not scaled, and inputs of length 0 or 1 come back unchanged (as complex). The values agree to rounding. The differences: every length runs in O(n log n) (R's code is quadratic in a large prime factor), real input uses a real transform, and threads follow fft_workers().

Usage

fft_stats(z, inverse = FALSE)

mvfft_stats(z, inverse = FALSE)

Arguments

z

A real or complex vector or array (fft_stats()), or matrix (mvfft_stats()).

inverse

TRUE for the unnormalised inverse transform. NA means forward, as in stats::fft().

Value

A complex vector, array or matrix with the attributes of z.

Details

A package moves by replacing fft( with zufft::fft_stats( and adding zufft to Imports.

Examples

x <- 1:4
fft_stats(x)
#> [1] 10+0i -2+2i -2+0i -2-2i
fft_stats(fft_stats(x), inverse = TRUE) / length(x)
#> [1] 1+0i 2+0i 3+0i 4+0i
all.equal(fft_stats(x), stats::fft(x))
#> [1] TRUE

m <- matrix(rnorm(12), 4)
all.equal(mvfft_stats(m), stats::mvfft(m))
#> [1] TRUE