/usr/share/octave/packages/communications-1.2.0/wgn.m is in octave-communications-common 1.2.0-1build1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 | ## Copyright (C) 2002 David Bateman
##
## This program is free software; you can redistribute it and/or modify it under
## the terms of the GNU General Public License as published by the Free Software
## Foundation; either version 3 of the License, or (at your option) any later
## version.
##
## This program is distributed in the hope that it will be useful, but WITHOUT
## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
## FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
## details.
##
## You should have received a copy of the GNU General Public License along with
## this program; if not, see <http://www.gnu.org/licenses/>.
## -*- texinfo -*-
## @deftypefn {Function File} {@var{y} =} wgn (@var{m}, @var{n}, @var{p})
## @deftypefnx {Function File} {@var{y} =} wgn (@var{m}, @var{n}, @var{p}, @var{imp})
## @deftypefnx {Function File} {@var{y} =} wgn (@var{m}, @var{n}, @var{p}, @var{imp}, @var{seed})
## @deftypefnx {Function File} {@var{y} =} wgn (@dots{}, @var{type})
## @deftypefnx {Function File} {@var{y} =} wgn (@dots{}, @var{output})
##
## Returns a M-by-N matrix @var{y} of white Gaussian noise. @var{p} specifies
## the power of the output noise, which is assumed to be referenced to an
## impedance of 1 Ohm, unless @var{imp} explicitly defines the impedance.
##
## If @var{seed} is defined then the randn function is seeded with this
## value.
##
## The arguments @var{type} and @var{output} must follow the above numerical
## arguments, but can be specified in any order. @var{type} specifies the
## units of @var{p}, and can be "dB", "dBW", "dBm" or "linear". "dB" is
## in fact the same as "dBW" and is keep as a misnomer of Matlab. The
## units of "linear" are in Watts.
##
## The @var{output} variable should be either "real" or "complex". If the
## output is complex then the power @var{p} is divided equally between the
## real and imaginary parts.
##
## @seealso{randn, awgn}
## @end deftypefn
function y = wgn (m, n, p, varargin)
if (nargin < 3 || nargin > 7)
print_usage ();
endif
if (!isscalar (m) || !isreal (m) || m < 0 || !isscalar (n) || ...
!isreal (n) || n < 0)
error ("wgn: M and N must be positive integers");
endif
type = "dBW";
out = "real";
imp = 1;
seed = [];
narg = 0;
for i = 1:length (varargin)
arg = varargin{i};
if (ischar (arg))
if (strcmp (arg, "real"))
out = "real";
elseif (strcmp (arg, "complex"))
out = "complex";
elseif (strcmp (arg, "dB"))
type = "dBW";
elseif (strcmp (arg, "dBW"))
type = "dBW";
elseif (strcmp (arg, "dBm"))
type = "dBm";
elseif (strcmp (arg, "linear"))
type = "linear";
else
error ("wgn: invalid argument '%s'", arg);
endif
else
narg++;
switch (narg)
case 1
imp = arg;
case 2
seed = arg;
otherwise
error ("wgn: too many arguments");
endswitch
endif
endfor
if (isempty (imp))
imp = 1;
elseif (!isscalar (imp) || !isreal (imp) || imp < 0)
error ("wgn: IMP must be a non-negative scalar");
endif
if (!isempty (seed))
if (! (isscalar (seed) && isreal (seed) && seed == fix (seed) && seed >= 0))
error ("wgn: random SEED must be integer");
endif
endif
if (!isscalar (p) || !isreal (p))
error ("wgn: P must be a scalar");
endif
if (strcmp (type, "linear") && p < 0)
error ("wgn: P must be a non-negative scalar for TYPE \"linear\"");
endif
if (strcmp (type, "dBW"))
np = 10^(p/10);
elseif (strcmp (type, "dBm"))
np = 10^((p - 30)/10);
elseif (strcmp (type, "linear"))
np = p;
endif
if (!isempty (seed))
randn ("state", seed);
endif
if (strcmp (out, "complex"))
y = (sqrt (imp*np/2)) * (randn (m, n) + 1i*randn (m, n));
else
y = (sqrt (imp*np)) * randn (m, n);
endif
endfunction
## Allow 30% error in standard deviation, due to randomness
%!assert (isreal (wgn (10, 10, 30, 1, "dBm", "real")));
%!assert (iscomplex (wgn (10, 10, 30, 1, "dBm", "complex")));
%!assert (abs (std (wgn (10000, 1, 30, 1, "dBm")) - 1) < 0.3);
%!assert (abs (std (wgn (10000, 1, 0, 1, "dBW")) - 1) < 0.3);
%!assert (abs (std (wgn (10000, 1, 1, 1, "linear")) - 1) < 0.3);
%% Test input validation
%!error wgn ();
%!error wgn (1);
%!error wgn (1, 1);
%!error wgn (1, 1, 1, 1, 1, 1);
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