issquare.m

JAVA 数学程序库 提供常规的数值计算程序包

## Copyright (C) 1996, 1997 John W. Eaton
##
## 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.
##
## 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, write to the Free
## Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
## 02110-1301, USA.

## -*- texinfo -*-
## @deftypefn {Function File} {} issquare (@var{x})
## If @var{x} is a square matrix, then return the dimension of @var{x}.
## Otherwise, return 0.
## @seealso{size, rows, columns, length, ismatrix, isscalar, isvector}
## @end deftypefn

## Author: A. S. Hodel <[e-mail]>
## Created: August 1993
## Adapted-By: jwe

function retval = issquare (x)

  retval = 0;

  if (nargin == 1)
    if (ismatrix (x) && ndims (x) < 3)
      [nr, nc] = size (x);
      if ((nr == nc) && (nr > 0))
        retval = nr;
      endif
    endif
  else
    usage ("issquare (x)");
  endif

endfunction

/*
@GROUP
general
@SYNTAX
issquare(values)
@DOC
.
@EXAMPLES
<programlisting>
issquare([88, 99; 33, 44])
issquare([22, 33])
</programlisting>
@NOTES
.
@SEE
ischar, iscell, isnumeric, isprime
*/