Suppose that A is an m by n integer matrix. Its Gram matrix is G = A*A^t. If A is not full rank, then G has some eigenvalues of 0. If I do G.LLL_gram() I get a somewhat uniformative error message like:
Value Error: ma matrix from Full MatrixSpace of 10 by 2 dense matrices over Integer Ring cannot be converted to a matrix in Full MatrixSpace of 10 by 10 dense matrices over Integer Ring! I understand that pari (which is what I understand, actually computes LLL_gram) doesn't like non-definite matrices. But, in this case it looks like it returned something to SAGE of lower dimension (what?) and SAGE didn't know what to do with it. Can the error message at least be changed to something more informative. I've found a work around for some of my matrices: Let N be some big integer, and let G'= N*G + identity_matrix(G.nrows()). This perturbs G a little so that the 0 eigenvalues go away. Victor -- You received this message because you are subscribed to the Google Groups "sage-support" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-support+unsubscr...@googlegroups.com. To post to this group, send email to sage-support@googlegroups.com. Visit this group at http://groups.google.com/group/sage-support?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
