## Copyright (C) 2007 Sylvain Pelissier <sylvain.pelissier@gmail.com>
##
## 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} {} ammod (@var{x}, @var{fc}, @var{fs})
## Create the AM modulation of the signal x with carrier frequency fs. Where
## x is sample at frequency fs.
## @seealso{amdemod, fmmod, fmdemod}
## @end deftypefn

function y = ammod (x, fc, fs)

  if (nargin != 3)
    print_usage ();
  endif

  l = length (x);
  t = 0:1./fs:(l-1)./fs;
  y = x .* cos (2.*pi.*fc.*t);

endfunction

%% Test input validation
%!error ammod ()
%!error ammod (1)
%!error ammod (1, 2)
%!error ammod (1, 2, 3, 4)
