update packages

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

diff --git a/octave_packages/m/statistics/distributions/unidpdf.m b/octave_packages/m/statistics/distributions/unidpdf.m
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+## Copyright (C) 2012 Rik Wehbring
+## Copyright (C) 2007-2012 David Bateman
+##
+## 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} {} unidpdf (@var{x}, @var{n})
+## For each element of @var{x}, compute the probability density function
+## (PDF) at @var{x} of a discrete uniform distribution which assumes
+## the integer values 1--@var{n} with equal probability.
+##
+## Warning: The underlying implementation uses the double class and
+## will only be accurate for @var{n} @leq{} @code{bitmax} 
+## (@w{@math{2^{53} - 1}} on IEEE-754 compatible systems).
+## @end deftypefn
+
+function pdf = unidpdf (x, n)
+
+  if (nargin != 2)
+    print_usage ();
+  endif
+
+  if (! isscalar (n))
+    [retval, x, n] = common_size (x, n);
+    if (retval > 0)
+      error ("unidpdf: X and N must be of common size or scalars");
+    endif
+  endif
+
+  if (iscomplex (x) || iscomplex (n))
+    error ("unidpdf: X and N must not be complex");
+  endif
+
+  if (isa (x, "single") || isa (n, "single"))
+    pdf = zeros (size (x), "single");
+  else
+    pdf = zeros (size (x));
+  endif
+
+  k = isnan (x) | ! (n > 0 & n == fix (n));
+  pdf(k) = NaN;
+
+  k = !k & (x >= 1) & (x <= n) & (x == fix (x));
+  if (isscalar (n))
+    pdf(k) = 1 / n;
+  else
+    pdf(k) = 1 ./ n(k);
+  endif
+
+endfunction
+
+
+%!shared x,y
+%! x = [-1 0 1 2 10 11];
+%! y = [0 0 0.1 0.1 0.1 0];
+%!assert(unidpdf (x, 10*ones(1,6)), y);
+%!assert(unidpdf (x, 10), y);
+%!assert(unidpdf (x, 10*[0 NaN 1 1 1 1]), [NaN NaN y(3:6)]);
+%!assert(unidpdf ([x, NaN], 10), [y, NaN]);
+
+%% Test class of input preserved
+%!assert(unidpdf (single([x, NaN]), 10), single([y, NaN]));
+%!assert(unidpdf ([x, NaN], single(10)), single([y, NaN]));
+
+%% Test input validation
+%!error unidpdf ()
+%!error unidpdf (1)
+%!error unidpdf (1,2,3)
+%!error unidpdf (ones(3),ones(2))
+%!error unidpdf (ones(2),ones(3))
+%!error unidpdf (i, 2)
+%!error unidpdf (2, i)
+