egison-5.1.0: lib/math/geometry/3d-euclidean-space.egi

def coordinates {Ring a} : Vector a := [x, y, z]

def metric {Ring a} : Matrix a :=
  generateTensor
    (\match as list integer with
      | [$n, #n] -> 1
      | _        -> 0)
    [3, 3]