Problems in engineering, computational science, and the physical, chemical, and biological sciences are using increasingly sophisticated mathematical techniques. Computer simulators are continuously confronted with questions concerning the choice of technique, given the enormous variety of available computational tools. To make a rational choice, a good understanding of the physics and algorithms behind each technique is essential.ntinuously confronted with questions concerning the choice of technique, given the enormous variety of available computational tools. To make a rational choice, a good understanding of the physics and algorithms behind each technique is essential.