--- /dev/null
+function p = tcdf(x,n)
+% TCDF returns student cumulative distribtion function
+%
+% cdf = tcdf(x,DF);
+%
+% Computes the CDF of the students distribution
+% with DF degrees of freedom
+% x,DF must be matrices of same size, or any one can be a scalar.
+%
+% see also: NORMCDF, TPDF, TINV
+
+% Reference(s):
+
+% $Id: tcdf.m 9033 2011-11-08 20:58:07Z schloegl $
+% Copyright (C) 2000-2003,2009 by Alois Schloegl <alois.schloegl@gmail.com>
+% This is part of the NaN-toolbox. For more details see
+% 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/>.
+
+
+% check size of arguments
+if all(size(x)==1)
+ x = repmat(x,size(n));
+elseif all(size(n)==1)
+ n = repmat(n,size(x));
+elseif all(size(x)==size(n))
+ ; %% OK, do nothing
+else
+ error('size of input arguments must be equal or scalar')
+end;
+
+% allocate memory
+p = zeros(size(x));
+p((x==Inf) & (n>0)) = 1;
+
+% workaround for invalid arguments in BETAINC
+ix = isnan(x) | ~(n>0);
+p(ix)= NaN;
+
+ix = (x > -Inf) & (x < Inf) & (n > 0);
+p(ix) = betainc (n(ix) ./ (n(ix) + x(ix).^2), n(ix)/2, 1/2) / 2;
+
+ix = find(x>0);
+p(ix) = 1 - p(ix);
+
+% shape output
+p = reshape(p,size(x));
+
+%!assert(tcdf(NaN,4),NaN)