This command is used to construct a KrylovNewton algorithm object which uses a modified Newton method with Krylov subspace acceleration to advance to the next time step.
algorithm KrylovNewton
The accelerator is described by Carlson and Miller in "Design and Application of a 1D GWMFE Code" from SIAM Journal of Scientific Computing (Vol. 19, No. 3, pp. 728-765, May 1998).