## Copyright (C) 1995, 1996, 1997  Friedrich Leisch
##
## 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 2, or (at your option)
## any later version.
##
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## 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, write to the Free
## Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
## 02110-1301, USA.

## -*- texinfo -*-
## @deftypefn {Function File} {} run_count (@var{x}, @var{n})
## Count the upward runs along the first non-singleton dimension of
## @var{x} of length 1, 2, ..., @var{n}-1 and greater than or equal 
## to @var{n}. If the optional argument @var{dim} is given operate
## along this dimension
## @end deftypefn

## Author: FL <Friedrich.Leisch@ci.tuwien.ac.at>
## Description: Count upward runs

function retval = run_count (x, n, dim)

  if (nargin != 2 && nargin != 3)
    usage ("run_count (x, n) or run_count (x, n, dim)");
  endif

  nd = ndims (x);
  sz = size (x);
  if (nargin != 3)
    ## Find the first non-singleton dimension.
    dim  = 1;
    while (dim < nd + 1 && sz(dim) == 1)
      dim = dim + 1;
    endwhile
    if (dim > nd)
      dim = 1;
    endif
  else
    if (! (isscalar (dim) && dim == round (dim))
	&& dim > 0
	&& dim < (nd + 1))
      error ("run_count: dim must be an integer and valid dimension");
    endif
  endif

  if (! (isscalar (n) && n == round (n)) && n > 0)
    error ("run_count: n must be a positive integer");
  endif
  
  nd = ndims (x);
  if (dim != 1)
    perm = [1 : nd];
    perm(1) = dim;
    perm(dim) = 1;
    x = permute (x, perm);
  endif

  sz = size (x);
  idx = cell ();
  for i = 1 : nd
    idx{i} = 1 : sz(i);
  endfor
  c = sz(1); 
  tmp = zeros ([c + 1, sz(2 : end)]);
  infvec = Inf * ones ([1, sz(2 : end)]);

  ind = find (diff ([infvec; x; -infvec]) < 0);
  tmp(ind(2:end) - 1) = diff(ind);
  tmp = tmp(idx{:});

  sz(1) = n;
  retval = zeros (sz);
  for k = 1 : (n-1)
    idx{1} = k;
    retval(idx{:}) = sum (tmp == k);
  endfor
  idx{1} = n;
  retval (idx {:}) = sum (tmp >= n);

  if (dim != 1)
    retval = ipermute (retval, perm);
  endif

endfunction