Mercurial > octave-nkf
view scripts/statistics/distributions/wblpdf.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 | 4d917a6a858b |
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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} {} wblpdf (@var{x}) ## @deftypefnx {Function File} {} wblpdf (@var{x}, @var{scale}) ## @deftypefnx {Function File} {} wblpdf (@var{x}, @var{scale}, @var{shape}) ## Compute the probability density function (PDF) at @var{x} of the ## Weibull distribution with scale parameter @var{scale} and shape ## parameter @var{shape} which is given by ## @tex ## $$ {shape \over scale^{shape}} \cdot x^{shape-1} \cdot e^{-({x \over scale})^{shape}} $$ ## @end tex ## @ifnottex ## ## @example ## shape * scale^(-shape) * x^(shape-1) * exp (-(x/scale)^shape) ## @end example ## ## @end ifnottex ## @noindent ## for @var{x} @geq{} 0. ## ## Default values are @var{scale} = 1, @var{shape} = 1. ## @end deftypefn ## Author: KH <Kurt.Hornik@wu-wien.ac.at> ## Description: PDF of the Weibull distribution function pdf = wblpdf (x, scale = 1, shape = 1) if (nargin < 1 || nargin > 3) print_usage (); endif if (!isscalar (scale) || !isscalar (shape)) [retval, x, scale, shape] = common_size (x, scale, shape); if (retval > 0) error ("wblpdf: X, SCALE, and SHAPE must be of common size or scalars"); endif endif if (iscomplex (x) || iscomplex (scale) || iscomplex (shape)) error ("wblpdf: X, SCALE, and SHAPE must not be complex"); endif if (isa (x, "single") || isa (scale, "single") || isa (shape, "single")) pdf = NaN (size (x), "single"); else pdf = NaN (size (x)); endif ok = ((scale > 0) & (scale < Inf) & (shape > 0) & (shape < Inf)); k = (x < 0) & ok; pdf(k) = 0; k = (x >= 0) & (x < Inf) & ok; if (isscalar (scale) && isscalar (shape)) pdf(k) = (shape * (scale .^ -shape) .* (x(k) .^ (shape - 1)) .* exp (- (x(k) / scale) .^ shape)); else pdf(k) = (shape(k) .* (scale(k) .^ -shape(k)) .* (x(k) .^ (shape(k) - 1)) .* exp (- (x(k) ./ scale(k)) .^ shape(k))); endif endfunction %!shared x,y %! x = [-1 0 0.5 1 Inf]; %! y = [0, exp(-x(2:4)), NaN]; %!assert(wblpdf (x, ones(1,5), ones(1,5)), y); %!assert(wblpdf (x, 1, ones(1,5)), y); %!assert(wblpdf (x, ones(1,5), 1), y); %!assert(wblpdf (x, [0 NaN Inf 1 1], 1), [NaN NaN NaN y(4:5)]); %!assert(wblpdf (x, 1, [0 NaN Inf 1 1]), [NaN NaN NaN y(4:5)]); %!assert(wblpdf ([x, NaN], 1, 1), [y, NaN]); %% Test class of input preserved %!assert(wblpdf (single([x, NaN]), 1, 1), single([y, NaN])); %!assert(wblpdf ([x, NaN], single(1), 1), single([y, NaN])); %!assert(wblpdf ([x, NaN], 1, single(1)), single([y, NaN])); %% Test input validation %!error wblpdf () %!error wblpdf (1,2,3,4) %!error wblpdf (ones(3),ones(2),ones(2)) %!error wblpdf (ones(2),ones(3),ones(2)) %!error wblpdf (ones(2),ones(2),ones(3)) %!error wblpdf (i, 2, 2) %!error wblpdf (2, i, 2) %!error wblpdf (2, 2, i)