[docs]
class EdgeCoeffs:
"""
a simple container class to hold edge-centered coefficients
and restrict them to coarse levels
"""
def __init__(self, g, eta, empty=False):
self.grid = g
if not empty:
eta_x = g.scratch_array()
eta_y = g.scratch_array()
# the eta's are defined on the interfaces, so
# eta_x[i,j] will be eta_{i-1/2,j} and
# eta_y[i,j] will be eta_{i,j-1/2}
b = (0, 1)
eta_x.v(buf=b)[:, :] = 0.5*(eta.ip(-1, buf=b) + eta.v(buf=b))
eta_y.v(buf=b)[:, :] = 0.5*(eta.jp(-1, buf=b) + eta.v(buf=b))
eta_x /= g.dx**2
eta_y /= g.dy**2
self.x = eta_x
self.y = eta_y
[docs]
def restrict(self):
"""
restrict the edge values to a coarser grid. Return a new
EdgeCoeffs object
"""
cg = self.grid.coarse_like(2)
c_edge_coeffs = EdgeCoeffs(cg, None, empty=True)
c_eta_x = cg.scratch_array()
c_eta_y = cg.scratch_array()
fg = self.grid
b = (0, 1, 0, 0)
c_eta_x.v(buf=b)[:, :] = 0.5*(self.x.v(buf=b, s=2) + self.x.jp(1, buf=b, s=2))
b = (0, 0, 0, 1)
c_eta_y.v(buf=b)[:, :] = 0.5*(self.y.v(buf=b, s=2) + self.y.ip(1, buf=b, s=2))
# redo the normalization
c_edge_coeffs.x = c_eta_x*fg.dx**2/cg.dx**2
c_edge_coeffs.y = c_eta_y*fg.dy**2/cg.dy**2
return c_edge_coeffs