show_x3d(
[create_surface((x, z) => [x, (x ** 2 - z ** 2) / 2, z], [-2, 2], [-2, 2])],
{
nav_type: "turntable",
viewpoint: {
position: '5.889397080091685 2.7934326318752367 -7.721164007228263',
orientation: '-0.047108402650163674 0.9891098499931613 0.13943637633794195,2.496586810720501'
}
}
)