% Find size of signal array in sqw object
% 
%   >> sz = sigvar_size (w)
%%   Overloaded methods:
%      sqw/sigvar_size
%      testsigvar/sigvar_size
%      sigvar/sigvar_size
%      IX_dataset_3d/sigvar_size
%      IX_dataset_2d/sigvar_size
%      IX_dataset_1d/sigvar_size
%      sqw/sigvar_size
%      sigvar/sigvar_size
%      d4d/sigvar_size
%      d3d/sigvar_size
%      d2d/sigvar_size
%      d1d/sigvar_size
%      d0d/sigvar_size
%