Sample frequencies

fft_freq() returns the frequency of each entry of a length-n transform from fft_c2c(), in cycles per unit of the sample spacing d: 0, 1, ..., ceiling(n / 2) - 1, -floor(n / 2), ..., -1, divided by d * n. fft_rfreq() returns the frequencies of the n %/% 2 + 1 entries of fft_r2c(): 0, 1, ..., n %/% 2, divided by d * n. They are SciPy's fftfreq() and rfftfreq().

Usage

fft_freq(n, d = 1)

fft_rfreq(n, d = 1)

Arguments

n

The transform length, a positive whole number.

d

The sample spacing, a positive number.

Value

A double vector.

See also

Other helpers: fft_next_len(), fft_shift()

Examples

fft_freq(8)
#> [1]  0.000  0.125  0.250  0.375 -0.500 -0.375 -0.250 -0.125
fft_freq(7, d = 0.1)
#> [1]  0.000000  1.428571  2.857143  4.285714 -4.285714 -2.857143 -1.428571
fft_rfreq(8)
#> [1] 0.000 0.125 0.250 0.375 0.500