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The data set used to illustrate subroutine en is taken from Example 10.5. The output generated by the program is presented in Output 10.3.

Output 10.3. Solution of the diffusion equation by the CN method

1 0.0 0.00 20.00 40.00 60.00 80.00100.00 80.00 60.00 40.00 20.00 0.00 3 1.0 0.00 19.92 39.59 58.20 72.93 78.79 72.93 58.20 39.59 19.92 0.00 5 2.0 0.00 19.34 37.76 53.75 64.97 69.06 64.97 53.75 37.7619.34 0.00 7 3.0 0.00 18.19 35.06 49.04 58.41 61.72 58.41 49.04 35.06 18.19 0.00 9 4.0 0.00 16.80 32.15 44.59 52.74 55.59 52.74 44.59 32.15 16.80 0.00

11 5.0 0.00 15.36 29.30 40.48 47.73 50.24 47.73 40.48 29.30 15.36 0.00 13 6.0 0.00 13.9826.64 36.73 43.23 45.48 43.23 36.7326.64 13.98 0.00 15 7.0 0.00 12.7024.1833.31 39.18 41.21 39.1833.31 24.1812.70 0.00 17 8.0 0.00 11.53 21.94 30.21 35.52 37.35 35.52 30.21 21.94 11.53 0.00 19 9.0 0.00 10.46 19.90 27.39 32.21 33.86 32.21 27.39 19.90 10.46 0.00 21 10.0 0.00 9.49 18.04 24.84 29.20 30.7029.20 24.84 18.04 9.49 0.00

Numerous libraries and software packages are available for solving the diffusion equation. Many work stations and main frame computers have such libraries attached to their operating systems.