nfct_1d: 1-D Non-Uniform Fast Cosine/Sine Tranform

In gzt/rNFFT: Fast Fourier Transform at Nonequispaced Nodes

Description

Similar to the NFFT, except the cosine/sine transform instead of the FFT. Note that all values of x must be in [0,1/2).

Usage

nfct_1d(x, f_hat)

nfct_adjoint_1d(x, f, n)

nfst_1d(x, f_hat)

nfst_adjoint_1d(x, f, n)

Arguments

x	(real) vector of nodes of length m, must be in [-0.5,0.5).
f_hat	(complex) vector of f_hat entries - (of length n) and length must be even.
f	frequencies for adjoint, same length as x
n	number of frequencies for transform, specified for adjoint.

Functions

• nfct_adjoint_1d: The adjoint transform

• nfst_1d: The sine transform

• nfst_adjoint_1d: The adjoint sine transform

Examples

set.seed(20190722)
x <- runif(19) * 0.5
f_hat = runif(14)

nfct_1d(x, f_hat)
nfst_1d(x, f_hat)
f <- nfct_1d(x, f_hat)
g <- nfst_1d(x, f_hat)
nfct_adjoint_1d(x,f,14)
nfst_adjoint_1d(x,g,14) # note the length!

gzt/rNFFT documentation built on April 15, 2020, 6:07 p.m.