Two solvers for non-symmetric SLAEs

The implementation of the biconjugate and the squared conjugate gradient (BiCG and CGS) preconditioned iterative methods are described for solving non-symmetric systems of linear algebraic equations (SLAEs) which arise when approximating multi-dimensional boundary value problems (BVPs) for diffusion-convection partial differential equations (PDEs), by finite eifference, finite element and finite volume methods (FDM, FEM and FVM). The results of numerical experiments are discussed.