Mercurial > octave-nkf
view scripts/statistics/distributions/expinv.m @ 14138:72c96de7a403 stable
maint: update copyright notices for 2012
author | John W. Eaton <jwe@octave.org> |
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date | Mon, 02 Jan 2012 14:25:41 -0500 |
parents | 19b9f17d22af |
children | f3d52523cde1 |
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## Copyright (C) 2012 Rik Wehbring ## Copyright (C) 1995-2012 Kurt Hornik ## ## This file is part of Octave. ## ## Octave 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. ## ## Octave 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 Octave; see the file COPYING. If not, see ## <http://www.gnu.org/licenses/>. ## -*- texinfo -*- ## @deftypefn {Function File} {} expinv (@var{x}, @var{lambda}) ## For each element of @var{x}, compute the quantile (the inverse of the ## CDF) at @var{x} of the exponential distribution with mean @var{lambda}. ## @end deftypefn ## Author: KH <Kurt.Hornik@wu-wien.ac.at> ## Description: Quantile function of the exponential distribution function inv = expinv (x, lambda) if (nargin != 2) print_usage (); endif if (!isscalar (lambda)) [retval, x, lambda] = common_size (x, lambda); if (retval > 0) error ("expinv: X and LAMBDA must be of common size or scalars"); endif endif if (iscomplex (x) || iscomplex (lambda)) error ("expinv: X and LAMBDA must not be complex"); endif if (!isscalar (x)) sz = size (x); else sz = size (lambda); endif if (iscomplex (x) || iscomplex (lambda)) error ("expinv: X and LAMBDA must not be complex"); endif if (isa (x, "single") || isa (lambda, "single")) inv = NaN (size (x), "single"); else inv = NaN (size (x)); endif k = (x == 1) & (lambda > 0); inv(k) = Inf; k = (x >= 0) & (x < 1) & (lambda > 0); if isscalar (lambda) inv(k) = - lambda * log (1 - x(k)); else inv(k) = - lambda(k) .* log (1 - x(k)); endif endfunction %!shared x %! x = [-1 0 0.3934693402873666 1 2]; %!assert(expinv (x, 2*ones(1,5)), [NaN 0 1 Inf NaN], eps); %!assert(expinv (x, 2), [NaN 0 1 Inf NaN], eps); %!assert(expinv (x, 2*[1 0 NaN 1 1]), [NaN NaN NaN Inf NaN], eps); %!assert(expinv ([x(1:2) NaN x(4:5)], 2), [NaN 0 NaN Inf NaN], eps); %% Test class of input preserved %!assert(expinv ([x, NaN], 2), [NaN 0 1 Inf NaN NaN], eps); %!assert(expinv (single([x, NaN]), 2), single([NaN 0 1 Inf NaN NaN]), eps); %!assert(expinv ([x, NaN], single(2)), single([NaN 0 1 Inf NaN NaN]), eps); %% Test input validation %!error expinv () %!error expinv (1) %!error expinv (1,2,3) %!error expinv (ones(3),ones(2)) %!error expinv (ones(2),ones(3)) %!error expinv (i, 2) %!error expinv (2, i)