Numerical techniques to improve lattice QCD calculations

I will be talking about numerical techniques which improve lattice QCD disconnected loop calculations.~We use an evaluation technique where the lattice matrix is projected over the multiple noises to obtain solution vectors. This is done with linear equation solvers like GMRES-DR (Generalized Minimum RESidual algorithm-Deflated and Restarted) for the first noise, and GMRES-Proj (similar algorithm projected over eigenvectors) for remaining noises. Noise subtraction methods that we are working on deflate out eigenvectors and fit a polynomial to the quark propagator to speed up calculations. A combination of deflation and polynomial methods gives the best results so far.