Plot Ackley function layers

ackley-3d.py

import numpy as np
import meshzoo
import meshio


def ackley(x):
    xx = np.einsum("i...,i...->...", x, x)
    sumcos = np.sum(np.cos(2 * np.pi * x), axis=0)
    return (
        -20.0 * np.exp(-0.2 * np.sqrt(0.5 * xx))
        - np.exp(0.5 * sumcos)
        + np.exp(1)
        + 20.0
    )


points, cells = meshzoo.cube_hexa(
    np.linspace(-5.0, 5.0, 101),
    np.linspace(-5.0, 5.0, 101),
    np.linspace(-5.0, 5.0, 101),
)
vals = ackley(points.T)

meshio.Mesh(points, {"hexahedron": cells}, point_data={"ackley": vals}).write("out.vtk")