Question in deriving equation

[MaxwellFang]

I am not sure how to derive from the second line to the third line, the best derivation I got is sum_{i, j} ui ortho(uj - ui). Also, if the third line is correct since the two vectors multiplied are orthogonal to each other, which leads the result to 0.

[alecjacobson]

Thank you for pointing this out. The derivation had some typos. Please see the updated readme for a more explicit and cleaner version:

[MaxwellFang]

Thank you for the explanation. Just one more question, why the last line contains an absolute value? Even in later discussion, U^T A U doesn't seem taking the absolute value either. Is that also a typo? Thank you

[alecjacobson]

It's not an absolute value it's the determinant.

…

On Mon, Apr 22, 2019, 11:52 PM MaxwellFang ***@***.***> wrote: Thank you for the explanation. Just one more question, why the last line contains an absolute value? Even in later discussion, U^T A U doesn't seem taken the absolute value either. Is that also a typo? Thank you — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#51 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AARDJGPKBTXZ4CKT4UIUQK3PR2BZLANCNFSM4HHMLP7A> .

[MaxwellFang]

Thanks for the explanation, I am going to close this issue