1 ## Copyright (C) 2003 David Bateman <adb014@gmail.com>
3 ## This program is free software; you can redistribute it and/or modify it under
4 ## the terms of the GNU General Public License as published by the Free Software
5 ## Foundation; either version 3 of the License, or (at your option) any later
8 ## This program is distributed in the hope that it will be useful, but WITHOUT
9 ## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 ## FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
13 ## You should have received a copy of the GNU General Public License along with
14 ## this program; if not, see <http://www.gnu.org/licenses/>.
17 ## @deftypefn {Function File} {@var{d} = } dftmtx (@var{n})
19 ## If @var{n} is a scalar, produces a @var{n}-by-@var{n} matrix @var{d}
20 ## such that the Fourier transform of a column vector of length @var{n}
21 ## is given by @code{dftmtx(@var{n}) * x} and the inverse Fourier transform
22 ## is given by @code{inv(dftmtx(@var{n})) * x}. In general this is less
23 ## efficient than calling the @dfn{fft} and @dfn{ifft} directly.
26 function d = dftmtx(n)
31 error ("dftmtx: argument must be scalar");