Merge branch 'master' of github.com:khanh101/khanh101.github.io

Author: khanh101

assets/header.tex

@@ -79,6 +79,7 @@
 \DeclareMathOperator{\Var}{Var}
 \DeclareMathOperator{\Cov}{Cov}
 \DeclareMathOperator{\RV}{RV}
+\DeclareMathOperator{\rank}{rank}
 
 %% pair delimiter
 \DeclarePairedDelimiter{\abs}{\lvert}{\rvert}