A CG Method for Multiple Right Hand Sides and Multiple Shifts in Lattice QCD Calculations

Understand

We consider the task of computing solutions of linear systems that only differ by a shift with the identity matrix as well as linear systems with several different right hand sides.

• In the past Krylov subspace methods have been developed which exploit either the need for solutions to multiple right hand sides (e.g.
• deflation type methods and block methods) or multiple shifts (e.g.
• shifted CG) with some success.