It's just a matter of definition, not truth. I've always seen positive definite defined as a condition on symmetric matrices, so that's what I take as the definition. —Dan Gene Salamin wrote: -----

On Tuesday, May 5, 2020, 09:58:03 AM PDT, Dan Asimov <dasimov@earthlink.net> wrote:

A positive definite matrix always means a *symmetric* matrix, ----- Not true. The nonsymmetric matrix [[a,b],[-b,c]] is positive definite when a > 0 and c > 0. -----