ABSTRACT
The first-order backward-time second-order centered-space (BTCS) approximation of Eq. (10.130) is given by Eq. (10.67):
A FORTRAN subroutine, subroutine btes, for solving the system equation arising from the application of Eq. (10.132) at every interior point in a finite difference grid is presented in Program 10.2. Subroutine thomas presented in Section 1.8.3 is used to solve the tridiagonal system equation. Only the statements which are different from the statements in program main and program fies in Section 10.12.1 are presented. Program main defines the data set and prints it, calls subroutine btes to implement the solution, and prints the solution.
