good_mg_cell_nr¶
- emg3d.meshes.good_mg_cell_nr(max_nr=1024, max_lowest=5, min_div=3)[source]¶
Return “good” cell numbers for the multigrid method.
“Good” cell numbers are numbers which can be divided by two as many times as possible. At the end there should be 2 or a small odd number.
The function adds all numbers
\[ \begin{align}\begin{aligned}p\ 2^n &\leq M \ , \text{ for}\\p &= {2, 3, ..., p_\text{max}} \ ;\\n &= {n_\text{min}, n_\text{min}+1, ..., \infty} \ ,\end{aligned}\end{align} \]where \(M, p_\text{max}, n_\text{min}\) correspond to
max_nr
,max_lowest
, andmin_div
, respectively.- Parameters
- max_nrint, default: 1024
Maximum number of cells.
- max_lowestint, default: 5
Maximum permitted lowest number p for p*2^n. {2, 3, 5, 7} are good upper limits in order to avoid too big lowest grids in the multigrid method.
- min_divint, default: 3
Minimum times the number can be divided by two.
- Returns
- numbersndarray
Array containing all possible cell numbers from lowest to highest.