This collection of papers on numerical analysis with special emphasis on nonlinear problems covers a broad spectrum of fields. Several papers are involved in applying numerical methods for proving the existence of solutions of nonlinear problems, e.g. of boundary problems or of obstacle problems. Naturally the solution of linear and nonlinear problems by iterative methods is the subject of a couple of papers. Here topics like the fast verification of solutions of monotone matrix equations, the convergence of linear asynchronous iteration with spectral radius of modulus one or aggregation and disaggregation methods for p-cyclic Markov chains are treated. On the other hand papers involved in optimization problems can be found. Nearly all fields of modern numerical analysis are touched by at least one paper.