%% Fill Output with NaN Values
% Create a vector of data, val, and a matrix of subscripts, subs.

val = 101:106';
subs = [1 1; 2 2; 3 3; 1 1; 2 2; 4 4]

% The subscripts in subs define a 4-by-4 matrix for the output, but only reference 4 out of the 16 elements. By default, the other 12 elements are 0 in the output.
%
% Use the fillval input of accumarray to fill in the extra output elements with NaN values.

A = accumarray(subs,val,[],[],NaN)

% The result is a 4-by-4 matrix padded with NaN values.
% Copyright 2012 The MathWorks, Inc.