def __init__(self, domain, equation, dt, u0, dtype=None):
# iterator
self.domain = domain
self.dt = dt
u0 = domain.to_points(u0)
self.PDE = Core.euler(domain, equation, dt, u0, dtype=dtype)
# figure:
self.fig = plt.figure(facecolor="#000000")
self.fig.labelcolor = '#FFFFFF'
self.ax1 = self.fig.add_subplot()
self.ax1.axis('off')
self.im1 = self.ax1.imshow(np.zeros(domain.shape))
# cspace
self.cspace = Graphic.ComplexMappable()
