2 method: 1-upwind, 2-leapfrog, 3-lax-wendroff
40 ntmax (max no of time steps)
2.0 tmax: max time for integration
-1.0 xmin
1.0 xmax
.10e-4 alpha: diffusion coefficient
0.6 s = alpha*dt/dx/dx
1.0 u (velocity)
0.5 c = u*dt/dx
2 nout: output every nout steps
1.0 f0: normalization of function (t=f0*fnew)
2 init: switch for initial condition
1.0 lambda: half wavelength for initial condition
0.5 fb0(1): boundary value at xmin (initially)
0.5 fb0(2): boundary value at xmax (initially)
1.0 fb1(1): boundary value at xmin
1.0 fb1(2): boundary value at xmax
40 maxex: no of terms in exact solution<=ntex