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fwht

Fast Walsh-Hadamard Transform

Description

Compute the (inverse) Fast Walsh-Hadamard transform of a signal.

Usage

ifwht(x, n = NROW(x), ordering = c("sequency", "hadamard", "dyadic"))

fwht(x, n = NROW(x), ordering = c("sequency", "hadamard", "dyadic"))

Arguments

x

input data, specified as a numeric vector or matrix. In case of a vector it represents a single signal; in case of a matrix each column is a signal. fwht operates only on signals with length equal to a power of 2. If the length of x is less than a power of 2, its length is padded with zeros to the next greater power of two before processing.
n

transform length, specified as a positive integer scalar. Default: NROW(x).
ordering

order of the Walsh-Hadamard transform coefficients, one of:

"sequency"

(Default) Coefficients in order of increasing sequency value, where each row has an additional zero crossing.

"hadamard"

Coefficients in normal Hadamard order

"dyadic"

Coefficients in Gray code order, where a single bit change occurs from one coefficient to the next

Value

(Inverse) Fast Walsh Hadamard transform, returned as a vector or matrix.

Author(s)

Mike Miller.
Conversion to R by Geert van Boxtel, G.J.M.vanBoxtel@gmail.com.

References

Examples

x <- c(19, -1, 11, -9, -7, 13, -15, 5)
X <- fwht(x)
all.equal(x, ifwht(X))
gsignal

Signal Processing

v0.3-1
GPL-3
Authors
Geert van Boxtel [aut, cre] (Maintainer), Tom Short [aut] (Author of 'signal' package), Paul Kienzle [aut] (Majority of the original sources), Ben Abbott [ctb], Juan Aguado [ctb], Muthiah Annamalai [ctb], Leonardo Araujo [ctb], William Asquith [ctb], David Bateman [ctb], David Billinghurst [ctb], Juan Pablo Carbajal [ctb], André Carezia [ctb], Vincent Cautaerts [ctb], Eric Chassande-Mottin [ctb], Luca Citi [ctb], Dave Cogdell [ctb], Carlo de Falco [ctb], Carne Draug [ctb], Pascal Dupuis [ctb], John W. Eaton [ctb], R.G.H Eschauzier [ctb], Andrew Fitting [ctb], Alan J. Greenberger [ctb], Mike Gross [ctb], Daniel Gunyan [ctb], Kai Habel [ctb], Kurt Hornik [ctb], Jake Janovetz [ctb], Alexander Klein [ctb], Peter V. Lanspeary [ctb], Bill Lash [ctb], Friedrich Leissh [ctb], Laurent S. Mazet [ctb], Mike Miller [ctb], Petr Mikulik [ctb], Paolo Neis [ctb], Georgios Ouzounis [ctb], Sylvain Pelissier [ctb], Francesco Potortì [ctb], Charles Praplan [ctb], Lukas F. Reichlin [ctb], Tony Richardson [ctb], Asbjorn Sabo [ctb], Thomas Sailer [ctb], Rolf Schirmacher [ctb], Rolf Schirmacher [ctb], Ivan Selesnick [ctb], Julius O. Smith III [ctb], Peter L. Soendergaard [ctb], Quentin Spencer [ctb], Doug Stewart [ctb], P. Sudeepam [ctb], Stefan van der Walt [ctb], Andreas Weber [ctb], P. Sudeepam [ctb], Andreas Weingessel [ctb]
Initial release
2021-05-02

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