Table 1: Comparison of efficiency indices for different methods.

Iterative methods (1.2) (1.5) (1.6) (2.2) Number of steps 1 2 2 3 Rate of convergence 2 4 4 6 Number of functional evaluations The classical efficiency index Number of LU factorizations 1 2 2 1 Cost of LU factorizations (based on flops) Cost of linear systems (based on flops) Flops-like efficiency index