Recent content by de_student

Hi. Thanks for prompt answer. But my question is in the example there is not always [c]-member from row vector. like there is no x3 in the member (2x1-x2). How can I deal with that?

Hi all. I have a quick question In this wikilink en.wikipedia.org/wiki/Positive-definite_matrix in the first example I don't get how they get 2x1^2 -2x1x2+2x2^2-2x2x3+2x3^2 in the third line. Can anyone bother to explain? Thanks a lot