digitrevorder: Permute input to digit-reversed order
Description
Reorder the elements of the input vector in digit-reversed order.
Usage
digitrevorder(x, r, index.return = FALSE)
Value
The digit-reversed input vector. If index.return = TRUE, then
a list containing the digit-reversed input vector (y, and the
digit-reversed indices (i).
Arguments
x
input data, specified as a vector. The length of x must be an
integer power of r.
r
radix base used for the number conversion, which can be any integer
from 2 to 36. The elements of x are converted to radix r and
reversed.
index.return
logical indicating if the ordering index vector should be
returned as well. Default FALSE.
This function is useful for pre-ordering a vector of filter coefficients for
use in frequency-domain filtering algorithms, in which the fft and ifft
transforms are computed without digit-reversed ordering for improved run-time
efficiency.