Xenon mimics neuronal ischemic preconditioning by activating ATP sensitive potassium channels. This has made meldonium a possible pharmacological agent for ischemic preconditioning. This was thought to be a local effect and was termed local ischemic preconditioning. AICAR-dependent preconditioning is also mediated by an ATP-sensitive potassium channel and hemeoxygenase-dependent mechanism. In most cases, preconditioning is necessary to ensure fast convergence of the conjugate gradient method. D'yakonov suggested spectrally equivalent preconditioning and derived non-asymptotic convergence rate bounds. Constructing and applying preconditioning can be computationally expensive, however. Another prerequisite is good preconditioning for the inner algorithm. Sensory preconditioning is a phenomenon discussed using terms common in classical conditioning. The pairing of these two NS constitutes sensory preconditioning. For performances, the Schur complement method is combined with preconditioning, at least a diagonal preconditioner. Gradient descent also benefits from preconditioning, but this is not done as commonly. Note that the residual vector here is different from the residual vector without preconditioning. A common process of hot water extraction begins with preconditioning. Preconditioning is typically related to reducing a condition number of the problem.