function y = spar(x, realFlag)

% spar -- Convert array to "spar" form.
%  spar(x) returns a matrix whose rows list the indices
%   and complex values of the non-zero elements of array x.
%   The real and imaginary components are placed in separate
%   columns.  Trailing rows or columns of zeros are ignored.
%   See "help unspar" for the inverse conversion.
%  spar(x, realFlag) delivers only the real-component of x,
%   if realFlag is TRUE; no column for the imaginary-component
%   is returned.
 
% Copyright (C) 1999 Dr. Charles R. Denham, ZYDECO.
%  All Rights Reserved.
%   Disclosure without explicit written consent from the
%    copyright owner does not constitute publication.
 
% Version of 19-Aug-1999 14:10:59.
% Updated    24-Aug-1999 11:34:47.

if nargin < 1, help(mfilename), return, end
if nargin < 2, realFlag = 0; end

siz = size(x);
dim = length(siz);

ind = find(x);

sub = cell(1, dim);
[sub{:}] = ind2sub(siz, ind);

if ~realFlag
	result = zeros(length(ind), dim+2);
else
	result = zeros(length(ind), dim+1);
end

for j = 1:dim
	result(:, j) = sub{j};
end

if ~realFlag
	result(:, end-1) = real(x(ind));
	result(:, end) = imag(x(ind));
else
	result(:, end) = real(x(ind));
end

if nargout > 0
	y = result;
else
	disp(result)
	assignin('caller', 'ans', result)
end