If the components of the ScaLAPACK library are properly installed, one should obtain performance results that are consistent with the computation and communication capabilities of the application computer. It is therefore a recommended practice to check the quality of the installation of the ScaLAPACK components as well as the performance of the hardware. Testing and timing programs are provided with all of the ScaLAPACK software components to diagnose installation problems. The above selection method of the distribution parameters generally achieves within 25% of the best possible performance. A rapid performance evaluation can be made at this stage to verify that the performance results obtained are reasonable and coherent. Finer tuning of these parameters can, of course, improve performance further.