exporting sparse matrix or inverse of spconvert

[tinku99]

I want access to the 3 vectors representing rows, columns, and values of my
sparse matrix. 
Is there a way to get at these easier than having to iterate through the
nonsparse matrix? 

I am trying to find the orientation of the largest connected region in a
binary image as follows: 

I need a column and row vectors of the sparse matrix to feed fitellipse.m 
by fitzgibbon here: 
http://homepages.inf.ed.ac.uk/rbf/CVonline/LOCAL_COPIES/FITZGIBBON/ELLIPSE/

I am able to get the largest connected region with the following: 

% Copyright 2009 Naveen Garg (address@hidden)
% GPL V2 http://www.gnu.org/licenses/gpl-2.0.html

function largest_blob = maxregion(binary_image)
% $$$   return region with largest area for given binary image
  [labeled_image, num] = bwlabel(binary_image);
  [N, X]=imhist(labeled_image, num + 1);
  N(1) = 0;
  [max,index_max] = max(N);
  largest_blob = (labeled_image == (index_max - 1)); 

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