Acoustics equations with zero initial conditions, inflow at x=0, solid wall at x=1.

The inflow boundary conditions are set in bc1.f to be an incoming
wave of strength 0.5*sin(*ω**t*). The value of omega is specified in
setrun.py.

Note that after time 2*π* ⁄ *ω* the boundary conditions at the left are
replaced by extrapolation (outflow) boundary conditions.

Example [book/chap7/acouinflow] to accompany the book Finite Volume Methods for Hyperbolic Problems by R. J. LeVeque.

Converted to Clawpack 5.0 form in 2013.

Converted to Clawpack 5.4.0 form in 2017.