Question

I have a cell array which each cell is an n-by-n matrix. I want to delete the cells for which inv(cell{i}'*cell{i}) gives warning that matrix is close to singular.
Thank you

Answer 1

In general, removing elements is the easy part. If C is your array, removing cells specified by the indices in vector idx can be done by:

C(idx) = {};

Regarding your specific problem, to check if a matrix is “almost” singular or not can be done with rcond (if the result is close to zero, it’s probably singular). To apply it to all cells you can use cellfun in the following way:

idx = cellfun(@(x)(rcond(x' * x) < 1e-12), C);

Adjust the threshold value to your liking. The resulting idx is a logical array with 1s at the location of singular matrices. Use idx to remove these elements from C as shown above.