• • • • •

Nonunifonn grids in which !:J.t (or ax) is variable are considered later in the chapter. The subscript n is used to denote the physical grid points, that is, tn (or x,J Thus, grid point n corresponds to location tn (or xn ) in the solution domain D(t) [or D(x)]. The total number of grid points is denoted by nmax. For the remainder of this chapter, time t will be chosen as the independent variable. Similar results hold for steady space marching problems in which space x is the independent variable. All the results in tenns of time t can be applied directly to space x simply by changing t to x everywhere.