63 lines
1.8 KiB
Matlab
63 lines
1.8 KiB
Matlab
function p = tcdf(x,n)
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% TCDF returns student cumulative distribtion function
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%
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% cdf = tcdf(x,DF);
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%
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% Computes the CDF of the students distribution
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% with DF degrees of freedom
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% x,DF must be matrices of same size, or any one can be a scalar.
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%
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% see also: NORMCDF, TPDF, TINV
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% Reference(s):
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% $Id: tcdf.m 9033 2011-11-08 20:58:07Z schloegl $
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% Copyright (C) 2000-2003,2009 by Alois Schloegl <alois.schloegl@gmail.com>
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% Copyright (C) 2014 Dynare Team
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% This is part of the NaN-toolbox. For more details see
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% http://pub.ist.ac.at/~schloegl/matlab/NaN/
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% This program is free software; you can redistribute it and/or modify
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% it under the terms of the GNU General Public License as published by
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% the Free Software Foundation; either version 3 of the License, or
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% (at your option) any later version.
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%
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% This program is distributed in the hope that it will be useful,
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% but WITHOUT ANY WARRANTY; without even the implied warranty of
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% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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% GNU General Public License for more details.
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%
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% You should have received a copy of the GNU General Public License
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% along with this program; If not, see <http://www.gnu.org/licenses/>.
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% check size of arguments
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if all(size(x)==1)
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x = repmat(x,size(n));
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elseif all(size(n)==1)
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n = repmat(n,size(x));
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elseif all(size(x)==size(n))
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; %% OK, do nothing
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else
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error('size of input arguments must be equal or scalar')
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end;
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% allocate memory
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p = zeros(size(x));
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p((x==Inf) & (n>0)) = 1;
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% workaround for invalid arguments in BETAINC
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ix = isnan(x) | ~(n>0);
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p(ix)= NaN;
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ix = (x > -Inf) & (x < Inf) & (n > 0);
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p(ix) = betainc (n(ix) ./ (n(ix) + x(ix).^2), n(ix)/2, 1/2) / 2;
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ix = find(x>0);
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p(ix) = 1 - p(ix);
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% shape output
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p = reshape(p,size(x));
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%!assert(tcdf(NaN,4),NaN)
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