https://www.zhumengyao.com/scidraft/tags/identity/Recent content in Identity on SciDraft | A Hugo ThemeHugoenMon, 21 Sep 2026 16:22:00 +0900https://www.zhumengyao.com/scidraft/notes/demo-note-identity-variance/Mon, 21 Sep 2026 16:22:00 +0900https://www.zhumengyao.com/scidraft/notes/demo-note-identity-variance/<p><strong>Demo note.</strong> This note demonstrates what the <strong>SciDraft</strong> Hugo theme can do for academic and scientific publishing — for research institutions, researchers and students. Its content is demonstration material only: readers should ignore whether the demo content is correct.</p> <p>An identity is an equation that holds for every admissible value of its variables, and this one converts a variance into two expectations, which is often the difference between a quantity that can be estimated in one pass and one that cannot.</p>https://www.zhumengyao.com/scidraft/notes/demo-note-identity-woodbury/Mon, 21 Sep 2026 14:42:00 +0900https://www.zhumengyao.com/scidraft/notes/demo-note-identity-woodbury/<p><strong>Demo note.</strong> This note demonstrates what the <strong>SciDraft</strong> Hugo theme can do for academic and scientific publishing — for research institutions, researchers and students. Its content is demonstration material only: readers should ignore whether the demo content is correct.</p> <p>The Woodbury identity rewrites the inverse of a matrix plus a low-rank correction in terms of the inverse of the original matrix and a much smaller inverse. It is the algebraic fact behind every method that updates a large system cheaply.</p>