update packages

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

diff --git a/octave_packages/m/statistics/distributions/wblinv.m b/octave_packages/m/statistics/distributions/wblinv.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} {} wblinv (@var{x})
+## @deftypefnx {Function File} {} wblinv (@var{x}, @var{scale})
+## @deftypefnx {Function File} {} wblinv (@var{x}, @var{scale}, @var{shape})
+## Compute the quantile (the inverse of the CDF) at @var{x} of the
+## Weibull distribution with scale parameter @var{scale} and shape
+## parameter @var{shape}.
+##
+## Default values are @var{scale} = 1, @var{shape} = 1.
+## @end deftypefn
+
+## Author: KH <Kurt.Hornik@wu-wien.ac.at>
+## Description: Quantile function of the Weibull distribution
+
+function inv = wblinv (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 ("wblinv: X, SCALE, and SHAPE must be of common size or scalars");
+    endif
+  endif
+
+  if (iscomplex (x) || iscomplex (scale) || iscomplex (shape))
+    error ("wblinv: X, SCALE, and SHAPE must not be complex");
+  endif
+
+  if (isa (x, "single") || isa (scale, "single") || isa (shape, "single"))
+    inv = NaN (size (x), "single");
+  else
+    inv = NaN (size (x));
+  endif
+
+  ok = (scale > 0) & (scale < Inf) & (shape > 0) & (shape < Inf);
+
+  k = (x == 0) & ok;
+  inv(k) = 0;
+
+  k = (x == 1) & ok;
+  inv(k) = Inf;
+
+  k = (x > 0) & (x < 1) & ok;
+  if (isscalar (scale) && isscalar (shape))
+    inv(k) = scale * (- log (1 - x(k))) .^ (1 / shape);
+  else
+    inv(k) = scale(k) .* (- log (1 - x(k))) .^ (1 ./ shape(k));
+  endif
+
+endfunction
+
+
+%!shared x
+%! x = [-1 0 0.63212055882855778 1 2];
+%!assert(wblinv (x, ones(1,5), ones(1,5)), [NaN 0 1 Inf NaN], eps);
+%!assert(wblinv (x, 1, ones(1,5)), [NaN 0 1 Inf NaN], eps);
+%!assert(wblinv (x, ones(1,5), 1), [NaN 0 1 Inf NaN], eps);
+%!assert(wblinv (x, [1 -1 NaN Inf 1], 1), [NaN NaN NaN NaN NaN]);
+%!assert(wblinv (x, 1, [1 -1 NaN Inf 1]), [NaN NaN NaN NaN NaN]);
+%!assert(wblinv ([x(1:2) NaN x(4:5)], 1, 1), [NaN 0 NaN Inf NaN]);
+
+%% Test class of input preserved
+%!assert(wblinv ([x, NaN], 1, 1), [NaN 0 1 Inf NaN NaN], eps);
+%!assert(wblinv (single([x, NaN]), 1, 1), single([NaN 0 1 Inf NaN NaN]), eps("single"));
+%!assert(wblinv ([x, NaN], single(1), 1), single([NaN 0 1 Inf NaN NaN]), eps("single"));
+%!assert(wblinv ([x, NaN], 1, single(1)), single([NaN 0 1 Inf NaN NaN]), eps("single"));
+
+%% Test input validation
+%!error wblinv ()
+%!error wblinv (1,2,3,4)
+%!error wblinv (ones(3),ones(2),ones(2))
+%!error wblinv (ones(2),ones(3),ones(2))
+%!error wblinv (ones(2),ones(2),ones(3))
+%!error wblinv (i, 2, 2)
+%!error wblinv (2, i, 2)
+%!error wblinv (2, 2, i)
+