% -*- texinfo -*-
% @deftypefn {Function File} {} apkconst (@var{nsig})
% @deftypefnx {Function File} {} apkconst (@var{nsig},@var{amp})
% @deftypefnx {Function File} {} apkconst (@var{nsig},@var{amp},@var{phs})
% @deftypefnx {Function File} {} apkconst (@var{...},'n')
% @deftypefnx {Function File} {} apkconst (@var{...},@var{str})
% @deftypefnx {Function File} {@var{y} = } apkconst (@var{...})
%
% Plots a ASK/PSK signal constellation. Argument @var{nsig} is a real vector
% whose length determines the number of ASK radii in the constellation.
% The values of vector @var{nsig} determine the number of points in each
% ASK radii.
%
% By default the radii of each ASK modulated level is given by the index of
% @var{nsig}. The amplitudes can be defined explictly in the variable
% @var{amp}, which is a vector of the same length as @var{nsig}.
%
% By default the first point in each ASK radii has zero phase, and following
% points are coding in an anti-clockwise manner. If @var{phs} is defined then
% it is a vector of the same length as @var{nsig} defining the initial phase
% in each ASK radii.
%
% In addition @dfn{apkconst} takes two string arguments 'n' and and @var{str}.
% If the string 'n' is included in the arguments, then a number is printed
% next to each constellation point giving the symbol value that would be
% mapped to this point by the @dfn{modmap} function. The argument @var{str}
% is a plot style string (example 'r+') and determines the default gnuplot
% point style to use for plot points in the constellation.
%
% If @dfn{apskconst} is called with a return argument, then no plot is
% created. However the return value is a vector giving the in-phase and
% quadrature values of the symbols in the constellation.
% @end deftypefn
% @seealso{dmod,ddemod,modmap,demodmap}