# Rank-one correction

### From Glossary

This is an update to an approximation of a matrix, notably to the hessian inverse, by adding a matrix of rank 1 to it. This generally takes the form: where is a nonzero column vector (so is a rank 1 matrix).

This is an update to an approximation of a matrix, notably to the hessian inverse, by adding a matrix of rank 1 to it. This generally takes the form: where is a nonzero column vector (so is a rank 1 matrix).