Residual-Based Simpler Block GMRES for Nonsymmetric Linear Systems with Multiple Right-Hand Sides

Algorithm 5

Determination of (, , ) or (, , ).

Choose a relative deflation threshold .

Compute the SVD of as , with ,

 , ; or the SVD of as , with

 , , .

Select singular values of , such that ; or singular values of such that .

Define as ; or as .