TITLE: Can QR decomposition be used for matrix inversion?
QUESTION [6 upvotes]: Is there any simple algorithm for matrix inversion (that can be implemented using C/C++)?
Can QR decomposition be used for matrix inversion? How?

REPLY [15 votes]: Gauss–Jordan elimination can be used for matrix inversion.
A QR-decomposition can certainly be used for matrix inversion because if $A=QR$ then $A^{-1} = R^{-1} Q^{-1} = R^{-1} Q^{T}$ and $R^{-1}$ is easy to compute because $R$ is triangular.
But consider why you need to invert a matrix. In most cases, you don't: you just need to solve a linear system $Ax=b$. If $A=QR$ then this system is equivalent to $Rx = Q^T b$, which is easy to solve because $R$ is triangular.