CR decomposition

Definition

Linear Algebra ETH, p.83

Theorem 2.46

Calculation

Note that $R^{\prime }$ is just the Reduced row echelon form (or RREF) of $A$

Usage

This method can be used to save storage space for matrices. Instead of saving $n\times m$ entries, we only need $(n+m)r$ entries (works well when $r$ is small compare to $m,n$)