unknown matlab error

Hi there, I deal with pretty large sparse arrays. There the following error occurred where I have no explanation for:

>> M = sparse(17e6,17e6);

>> m = M(2.82e14);

??? Maximum variable size allowed by the program is exceeded.

although "numel(M) = 2.89e14".

Can anyone please bring light into this error message?

[Lars Ludwig]

the matrix is already sparse, the crucial point is that I use linear indexing... that only allows 48 bit integers

I pinned this issue down in a second question

[Andreas Goser]

I understand. My answer was purposly generic to be helpful for people that search for this error message.

Answer 1

[Andreas Goser]

You are attempting to create a matrix with more elements than the maximum number of elements allowed in MATLAB.

Common causes: MATLAB will attempt to create a matrix with a large number of elements, as long as that number of elements is less than the maximum number of elements allowed in a matrix. You can determine this maximum using the COMPUTER function in the following way.

[str, maxsize] = computer

Solution: If the matrix you are attempting to create has relatively few nonzero elements, you may be able to create it as a sparse matrix. You can use the SPARSE function and the other sparse matrix manipulation functions to create and manage this matrix. Type

help sparfun

for a list of the sparse matrix manipulation functions. Note, however, that the limitation on the maximum number of elements still exists; now it only applies to the nonzero elements of the sparse matrix. If your matrix is not sparse, however, you will need to break it into sections with a number of elements less than the maximum returned by the COMPUTER function.