The Sherman-Morrison formula is a formula that allows a perturbed matrix to be computed for a change to a given matrix . If the change can be written in the form
for two vectors and , then the Sherman-Morrison formula is
where
More things to try:
Weisstein, Eric W. "Sherman-Morrison Formula." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/Sherman-MorrisonFormula.html