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## Copyright (C) 2012 CarnĂŤ Draug <carandraug+dev@gmail.com>
##
## This program 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.
##
## This program 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
## this program; if not, see <http://www.gnu.org/licenses/>.
## -*- texinfo -*-
## @deftypefn {Function File} {@var{Pr} =} minmax (@var{Pp})
## Calculate maximum and mininum of rows.
##
## For each row of the matrix @var{Pp}, outputs its minimum and maximum on the
## first and second column of @var{Pr} respectively. @var{Pr} will have the
## same number of rows as @var{Pp} and 2 columns.
##
## @group
## @example
## Pp = [5 7 9 2 5 0 6
## 5 3 6 2 7 9 3
## 8 3 2 3 5 6 8]
## minmax (Pp)
## @result{} 0 9
## 2 9
## 0 8
## @end example
## @end group
##
## @var{Pp} can also be a cell array of matrices in wich case they all must have
## the same number of columns, and all matrices on each row of cells must have
## the same number of rows. In this case, matrices of each row of @var{Pp} are
## concatenated horizontally for calculating the minimum ad maximum values.
## @var{Pr} will be a single column cell array with same number of rows as
## @var{Pp}. For example:
##
## @group
## @example
## Pp = @{[0 1; 1 2; 4 6] [2 3; 8 0; 3 1] [9 1; 5 2; 4 8];
## [1 2; 9 7] [5 2; 3 1] [7 6; 0 3]@}
## minmax (Pp)
## @result{} @{
## [1,1] =
## 0 9
## 0 8
## 1 8
## [2,1] =
## 1 7
## 0 9
## @}
## @end example
## @end group
##
## If drawn on a table, it would look like:
##
## @verbatim
## 2x3 cell array 2x1 cell array
##
## 0 1 2 3 9 1 > 0 9
## 1 2 8 0 5 2 > 0 8
## 4 6 3 1 4 8 > 1 8
##
## 1 2 5 2 7 6 > 1 7
## 9 7 3 1 0 3 > 0 9
## @end verbatim
##
## Note how on this example: the number of columns (3) in the cell array is
## irrelevant but the output has the same number of rows (2); all matrices have
## the same number of columns (2).
##
## @seealso {cell2mat, max, min}
## @end deftypefn
function Pr = minmax (Pp)
if (nargin != 1)
print_usage;
elseif (minmax_check (Pp))
Pr = single_minmax (Pp);
elseif (iscell (Pp) && ndims (Pp) == 2 && all (cellfun (@minmax_check, Pp(:))))
Pr_rows = cellfun (@rows, Pp(:,1));
if (!all (cellfun (@columns, Pp(:)) == columns (Pp{1})))
error ("minmax: all matrices must have the same number of columns.");
elseif (!all (bsxfun (@eq, cellfun (@rows, Pp), Pr_rows)(:)))
error ("minmax: all matrices in a row of cells must have same number of rows.");
endif
Pr = mat2cell (single_minmax (cell2mat (Pp)), Pr_rows, 2);
else
error ("minmax: input must be one, or a 2D cell array of, 2D non-complex matrix.");
endif
endfunction
function retval = minmax_check (val)
retval = isnumeric (val) && !iscomplex (val) && ndims (val) == 2;
endfunction
function Pr = single_minmax (Pp)
Pr = [min(Pp, [], 2) max(Pp, [], 2)];
endfunction
%!assert (minmax ([2 5 4; -2 6 5]), [2 5; -2 6]); # basic usage
%!assert (minmax ([2 5 4]), [2 5]); # single row, basic usage
%!assert (minmax ({[0 1; -1 -2; 34 56] [2 3; 8 0; 21 23]; [1 -2; 9 7] [12 5; 13 11]}), ...
%! {[0 3; -2 8; 21 56]; [-2 12; 7 13]}); # basic usage with cell arrays
%!assert (minmax (1), [1 1]); # matlab compatibility
%!fail ("minmax ([i 2; 3 4])"); # do not accept complex values
%!fail ("minmax (rand (2, 2, 2))"); # only 2D matrix
%!fail ("minmax ({[0 1; 1 2] [2 3 2; 8 0 2]; [1 2] [9 7 3]})"); # number of columns must be the same everywhere
%!fail ("minmax ({[0 1; 1 2] [2 3; 8 0; 5 5]; [1 2; 9 7] [1 5; 1 1]})"); # each row of cells must have matrices with same number of rows