get_hx¶

emg3d.meshes.get_hx(alpha, domain, nx, x0, resp_domain=True)[source]¶

Return cell widths for given input.

Find the number of cells left (nl) and right (nr) of the center x0 for the provided alpha. For this, we solve

\[\frac{x_\text{max}-x_0}{x_0-x_\text{min}} = \frac{a^\text{nr}-1}{a^\text{nl}-1}\]

where \(a = 1+\alpha\).

Parameters:

alpha : float: Stretching factor a is given by a=1+alpha.
domain : list: [x_min, x_max] of model domain.
nx : int: Number of cells.
x0 : float: Center of the grid. x0 is restricted to domain.
resp_domain : bool: If False, then the domain-end might shift slightly to assure that the same stretching factor is applied throughout. If set to True (default), however, the domain is respected absolutely. This will introduce one stretch-factor which is different from the other stretch factors, to accommodate the restriction. This one-off factor is between the left- and right-side of x0, or, if x1 is provided, just after x1.

Returns:

hx : ndarray: Cell widths of mesh. All points are given by np.r_[xmin, xmin+np.cumsum(hx)]