% -*- texinfo -*-
% @deftypefn {Function File} {[@var{p}, @var{y}] =} ppplot (@var{x}, @var{dist}, @var{params})
% Perform a PP-plot (probability plot).
%
% If F is the CDF of the distribution @var{dist} with parameters
% @var{params} and @var{x} a sample vector of length @var{n}, the
% PP-plot graphs ordinate @var{y}(@var{i}) = F (@var{i}-th largest
% element of @var{x}) versus abscissa @var{p}(@var{i}) = (@var{i} -
% 0.5)/@var{n}. If the sample comes from F, the pairs will
% approximately follow a straight line.
%
% The default for @var{dist} is the standard normal distribution. The
% optional argument @var{params} contains a list of parameters of
% @var{dist}. For example, for a probability plot of the uniform
% distribution on [2,4] and @var{x}, use
%
% @example
% ppplot (x, 'uniform', 2, 4)
% @end example
%
% @noindent
% @var{dist} can be any string for which a function @var{dist_cdf}
% that calculates the CDF of distribution @var{dist} exists.
%
% If no output arguments are given, the data are plotted directly.
% @end deftypefn