>>> import numpy as np
>>> import wavepacket as wp
>>>
>>> dof = wp.grid.PlaneWaveDof(-10, 20, 96)
>>> grid = wp.grid.Grid(dof)
>>>
>>> def absorbing_boundary(x):
...     potential = -10j * (x - 12.0) ** 2 / (20 - 12.0) ** 2
...     potential[x < 12] = 0
...     return potential
>>>
>>> kinetic = wp.operator.CartesianKineticEnergy(grid, 0, mass=1)
>>> absorber = wp.operator.Potential1D(grid, 0, absorbing_boundary)
>>> equation = wp.expression.SchroedingerEquation(kinetic + absorber)
>>> 
>>> psi0 = wp.builder.product_wave_function(grid, wp.special.Gaussian(-5, 2, rms=1))
>>> solver = wp.solver.OdeSolver(equation, 1)
>>> 
>>> for t, psi in solver.propagate(psi0, 0.0, 10):
...     wp.log(t, psi, precision=4, truncate=1e-10)
<BLANKLINE>
-----------------------------------------------
t = 0.0,     trace = 1.0
<BLANKLINE>
<x_0> = -5.0  +/- 0.7071
<BLANKLINE>
-----------------------------------------------
t = 1.0,     trace = 1.0
<BLANKLINE>
<x_0> = -3.0  +/- 1.0
<BLANKLINE>
-----------------------------------------------
t = 2.0,     trace = 1.0
<BLANKLINE>
<x_0> = -1.0  +/- 1.581
<BLANKLINE>
-----------------------------------------------
t = 3.0,     trace = 1.0
<BLANKLINE>
<x_0> = 1.0  +/- 2.236
<BLANKLINE>
-----------------------------------------------
t = 4.0,     trace = 0.9999
<BLANKLINE>
<x_0> = 2.999  +/- 2.914
<BLANKLINE>
-----------------------------------------------
t = 5.0,     trace = 0.996
<BLANKLINE>
<x_0> = 4.959  +/- 3.552
<BLANKLINE>
-----------------------------------------------
t = 6.0,     trace = 0.9615
<BLANKLINE>
<x_0> = 6.637  +/- 3.959
<BLANKLINE>
-----------------------------------------------
t = 7.0,     trace = 0.8678
<BLANKLINE>
<x_0> = 7.791  +/- 4.111
<BLANKLINE>
-----------------------------------------------
t = 8.0,     trace = 0.7319
<BLANKLINE>
<x_0> = 8.47  +/- 4.154
<BLANKLINE>
-----------------------------------------------
t = 9.0,     trace = 0.5905
<BLANKLINE>
<x_0> = 8.83  +/- 4.18
<BLANKLINE>
-----------------------------------------------
t = 10.0,     trace = 0.4666
<BLANKLINE>
<x_0> = 8.994  +/- 4.221
