Speaker
Description
A very simple approach to solving multiple right-hand side systems is proposed. For symmetric problems, the conjugate gradient method is a very efficient way to solve linear equations. We will use the same parameters from solving the first system for other systems. This is called Twin CG. It corresponds to applying the same polynomial to the other systems as was used for the first system. No dot products are needed except for the first system, and the method is very parallelizable. Deflation of eigenvalues using seeding can be included. The remarkable natural stability control due to roundoff error in the symmetric Lanczos iteration will be discussed. Added stability control methods include deflating eigenvalues with linear factors and applying partial Global CG.