% -*- texinfo -*-
% @deftypefn {Function File} {[@var{pval}, @var{f}, @var{df_num}, @var{df_den}] =} var_test (@var{x}, @var{y}, @var{alt})
% For two samples @var{x} and @var{y} from normal distributions with
% unknown means and unknown variances, perform an F-test of the null
% hypothesis of equal variances. Under the null, the test statistic
% @var{f} follows an F-distribution with @var{df_num} and @var{df_den}
% degrees of freedom.
%
% With the optional argument string @var{alt}, the alternative of
% interest can be selected. If @var{alt} is @code{'~='} or
% @code{'<>'}, the null is tested against the two-sided alternative
% @code{var (@var{x}) ~= var (@var{y})}. If @var{alt} is @code{'>'},
% the one-sided alternative @code{var (@var{x}) > var (@var{y})} is
% used. Similarly for '<', the one-sided alternative @code{var
% (@var{x}) > var (@var{y})} is used. The default is the two-sided
% case.
%
% The p-value of the test is returned in @var{pval}.
%
% If no output argument is given, the p-value of the test is displayed.
% @end deftypefn