update packages

[CreaPhase.git] / octave_packages / m / statistics / distributions / wblpdf.m

diff --git a/octave_packages/m/statistics/distributions/wblpdf.m b/octave_packages/m/statistics/distributions/wblpdf.m
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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)
+