If potrf is called on an indefinite matrix A are there any guarantees on what state it leaves A in when it returns?
For example, if the submatrix A'=A[0:k,0:k] is positive definite, but A[0:k+1,0:k+1] is not, can it be assumed that when potrf returns, the A[0:k,0:k] region of memory contains the cholesky factorization of A'?
This looks like it might be true, but I don't see any guarantees listed in the documentation (https://software.intel.com/en-us/node/520881). There are some algorithms that use the partial factorization to compute a bound on the smallest eigenvalue (For example More and Sorensen's algorithm in the paper "Computing a Trust Region Step"), so it would be helpful if such guarantees could be made as part of the contract of potrf