--- /dev/null
+function [h, pval, ci, stats, df] = ttest2 (x, y, alpha, tail, vartype, DIM)
+% TTEST2 (unpaired) t-test
+% For two samples x and y from normal distributions with unknown
+% means and unknown equal variances, perform a two-sample t-test of
+% the null hypothesis of equal means. Under the null, the test
+% statistic T follows a Student distribution with DF degrees of
+% freedom.
+%
+% TTEST2 treads NaNs as "Missing values" and ignores these.
+%
+% H = ttest2(x,y)
+% H = ttest2([x;y],C,W)
+% H = ttest2(x,y,alpha)
+% H = ttest2(x,y,alpha,tail)
+% H = ttest2(x,y,alpha,tail,vartype)
+% H = ttest2(x,y,alpha,tail,vartype,DIM)
+% [H,PVAL] = ttest2(...)
+% [h,p,ci,stats] = ttest2(...)
+%
+% H=1 indicates a rejection of the Null-hypothesis at a significance
+% level of alpha (default alpha = 0.05).
+%
+% With the optional argument string TAIL, the Alternative of interest
+% can be selected. If TAIL is '!=' or '<>' or 'both', the null is tested
+% against the two-sided Alternative `mean (X) ~= mean (Y)'. If TAIL
+% is '>' or 'right', the one-sided Alternative `mean (X) > mean (Y)' is used.
+% Similarly for '<' or 'left', the one-sided Alternative `mean (X) < mean
+% (Y)' is used. The default is the two-sided case.
+%
+% vartype support only 'equal' (default value); the value 'unequal' is not supported.
+%
+% H returns whether the Null-Hypotheses must be rejected.
+% The p-value of the test is returned in PVAL.
+%
+% TTEST2 works on the first non-singleton dimension or on DIM.
+%
+% If no output argument is given, the p-value of the test is
+% displayed.
+%
+
+%%% not supported yet
+% [h,p,ci] = ttest2(...)
+% [h,p,ci,stats] = ttest2(...)
+
+% $Id$
+% Copyright (C) 1995, 1996, 1997, 1998, 2000, 2002, 2005, 2006, 2007
+% Kurt Hornik
+% Copyright (C) 2010 by Alois Schloegl <alois.schloegl@gmail.com>
+% This function is part of the NaN-toolbox
+% http://pub.ist.ac.at/~schloegl/matlab/NaN/
+
+% 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/>.
+
+ if ((nargin < 2) || (nargin > 6) || nargout > 4)
+ print_usage ;
+ end
+
+ if (nargin < 3) || isempty(alpha)
+ alpha = .05;
+ W = [];
+ elseif size(x,1)==size(y,1) && size(x,1)==size(alpha,1) && size(y,2)==1 && all(y==1 | y==2)
+ c = y;
+ y = x(c==2,:);
+ x = x(c==1,:);
+ Wy = alpha(c==2);
+ Wx = alpha(c==1);
+ alpha = .05;
+ end
+
+ if (nargin < 4) || isempty(tail)
+ tail = '~=';
+ end
+ if (~ ischar (tail))
+ error ('ttest2: tail must be a string');
+ end
+ if (nargin < 5) || isempty(vartype)
+ vartype = 'equal';
+ end
+ if ~strcmp(vartype,'equal')
+ error ('test: vartype not supported')
+ end
+ if nargin<6,
+ DIM = find(size(x)>1,1);
+ end;
+ if isempty(DIM), DIM=1; end;
+
+ szx = size(x);
+ szy = size(y);
+ szy(DIM) = 1;
+ szx(DIM) = 1;
+
+ if (any(szx-szy))
+ error ('ttest2: dimension of X and Y do not fit');
+ end
+
+ [SX, NX] = sumskipnan(x, DIM, Wx);
+ [SY, NY] = sumskipnan(y, DIM, Wy);
+ stats.df = NX + NY - 2;
+ MX = SX ./ NX;
+ MY = SY ./ NY;
+
+ if any(size(x)==0) || any(size(y)==0)
+ v = NaN;
+ else
+ v = sumsq(x-repmat(MX,size(x)./size(MX))) + sumsq(y-repmat(MY,size(y)./size(MY)));
+ end;
+ stats.sd = sqrt(v/stats.df);
+ stats.tstat = (MX - MY) .* sqrt ((NX .* NY .* stats.df) ./ (v .* (NX + NY)));
+ cdf = tcdf (stats.tstat, stats.df);
+
+ if (strcmp (tail, '~=') || strcmp (tail, '!=') || strcmp (tail, '<>')) || strcmp(tail,'both'),
+ pval = 2 * min (cdf, 1 - cdf);
+ elseif strcmp (tail, '>') || strcmp(tail,'right'),
+ pval = 1 - cdf;
+ elseif strcmp (tail, '<') || strcmp(tail,'left'),
+ pval = cdf;
+ else
+ error ('ttest2: option %s not recognized', tail);
+ end
+
+ h = pval < alpha;
+
+ if (nargout == 0)
+ fprintf(1,' pval: %g\n', pval);
+ end
+