function [ndim,mdim]=fixdim(n,m)
% make sure vector n is length at least m by adding 1s if necessary
% to counter the unfortunate effect of size on multidimensional arrays
% also make sure mdim is at least 2
ln=length(n);
if ln>m,
    if any(n(m+1:ln)~=1),
        error('too many dimensions')
    end
end
if m==1,
    mdim=2;
else
    mdim=m;
end
ndim=[n,ones(1,mdim-ln)];