Collection of initial conditions

The function pulse in wave1D_dn_vc.py offers four initial conditions:

1. a rectangular pulse ("plug")
2. a Gaussian function (gaussian)
3. a "cosine hat": one period of $1 + \cos (\pi x$, $x\in [-1,1]$
4. half a "cosine hat": half a period of $\cos \pi x$, $x\in [-{\half},{\half}]$

>>> import wave1D_dn_vc as w
>>> w.pulse(loc='left', pulse_tp='cosinehat', Nx=50, every_frame=10)