## Copyright (C) 2002 Rolf Fabian <fabian@tu-cottbus.de>
##
## 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} {@var{s} =} mat2str (@var{x}, @var{n})
## @deftypefnx {Function File} {@var{s} =} mat2str (@dots{}, 'class')
##
## Format real/complex numerial matrices as strings. This function
## returns values that are suitable for the use of the @code{eval}
## function.
##
## The precision of the values is given by @var{n}. If @var{n} is a
## scalar then both real and imaginary parts of the matrix are printed
## to the same precision. Otherwise @code{@var{n} (1)} defines the
## precision of the real part and @code{@var{n} (2)} defines the
## precision of the imaginary part. The default for @var{n} is 17.
##
## If the argument 'class' is given, then the class of @var{x} is
## included in the string in such a way that the eval will result in the
## construction of a matrix of the same class.
##
## @example
## @group
##    mat2str( [ -1/3 + i/7; 1/3 - i/7 ], [4 2] )
##    @result{} '[-0.3333+0.14i;0.3333-0.14i]'
##    mat2str( [ -1/3 +i/7; 1/3 -i/7 ], [4 2] )
##    @result{} '[-0.3333+0i,0+0.14i;0.3333+0i,-0-0.14i]'
##    mat2str( int16([1 -1]), 'class')
##    @result{} 'int16([1,-1])'
## @end group
## @end example
##
## @seealso{sprintf, int2str}
## @end deftypefn

function s = mat2str(x,n,cls)

  if (nargin < 2 || isempty(n))
    n = 17;		   # default precision
  endif

  if (nargin < 3)
    if (ischar(n))
      cls = n;
      n = 17;
    else
      cls = '';
    endif
  endif

  if (nargin < 1 || nargin > 3 || ischar(x) || isstruct(x) ||
     ischar(n) || isstruct(n) || isstruct(cls))
    usage ("mat2str");
  endif
  
  if (ndims (x) > 2)
    error ("mat2str: x must be two dimensional");
  endif

  if (!(COMPLEX = is_complex(x)))
    FMT = sprintf("%%.%dg", n(1));
  else
    if (length(n) == 1 )
      n = [n, n];
    endif
    FMT = sprintf("%%.%dg%%+.%dgi", n(1), n(2));
  endif

  [nr, nc] = size(x);

  if (nr*nc == 0)         # empty .. only print brackets
    s = "[]";
  elseif (nr*nc == 1)	# scalar x .. don't print brackets
    if (!COMPLEX)
      s = sprintf( FMT, x );
    else
      s = sprintf( FMT, real(x), imag(x) );
    endif
  else			# non-scalar x .. print brackets
    FMT = [FMT, ','];
    if (!COMPLEX)
      s = sprintf( FMT, x.' );
    else
      x = x.';
      s = sprintf( FMT, [ real(x(:))'; imag(x(:))' ] );
    endif

    s = ["[", s];
    s (length(s)) = "]";
    IND = find(s == ",");
    s (IND(nc:nc:length(IND)) ) = ";";
  endif

  if (strcmp ("class", cls))
    s = [class(x), "(", s, ")"]
  endif
endfunction