 The CMA-ES implements a stochastic variable-metric method.In the very particular case of a convex-quadratic objective function

the covariance matrix formula_79 adapts to the inverse of the Hessian matrix formula_116, up to a scalar factor and small random fluctuations.More general, also on the function formula_117, where formula_118 is strictly increasing and therefore order preserving and formula_3 is convex-quadratic, the covariance matrix formula_79 adapts to formula_121, up to a scalar factor and small random fluctuations.