Surface cos(x) + cos(y)

Equation: z = cos(x) + cos(y)

z = cos(x) + cos(y) equals 2 on the 2π lattice and −2 on the π-shifted lattice. It is a simple periodic potential.

Compared with sin(x) cos(y), the cosine sum has clearer translational symmetry and does not flip sign row by row independently.

Related surfaces

• Twin peaksz = sin(x) * cos(y)
• Rolling wavesz = sin(x + t) + cos(y + t)
• Mexican hatz = (1 - (x^2 + y^2)/8) * exp(-(x^2 + y^2)/8)