17 September 2021   9:31:09.525 AM

FD1D_ADVECTION_LAX:
  FORTRAN90 version

  Solve the constant-velocity advection equation in 1D,
    du/dt = - c du/dx
  over the interval:
    0.0 <= x <= 1.0
  with periodic boundary conditions, and
  with a given initial condition
    u(0,x) = (10x-4)^2 (6-10x)^2 for 0.4 <= x <= 0.6
           = 0 elsewhere.

  We modify the FTCS approach using the Lax method:
    du/dt = (u(t+dt,x)-0.5*u(t,x-dx)-0.5*u(t,x+dx))/dt
    du/dx = (u(t,x+dx)-u(t,x-dx))/2/dx

  Number of nodes NX =    101
  Number of time steps NT =   1000
  Constant velocity C =    1.00000    
  CFL condition: dt (  0.100000E-02) <= dx / c (  0.100000E-01)

  Plot data written to the file "fd1d_advection_lax_data.txt".
  Gnuplot command data written to the file "fd1d_advection_lax_commands.txt".

FD1D_ADVECTION_LAX
  Normal end of execution.

17 September 2021   9:31:09.528 AM