For three-dimensional systems, a convention is to portray the x-y plane horizontally, with the z axis added to represent height (positive up).

Again, there is an ambiguity caused by projecting the three-dimensional coordinate system into the plane.

Instructional use was made of projected vectograph slides illustrating three-dimensional coordinate systems.

I show a three-dimensional coordinate system.

The name is a pun on the Cartesian three-dimensional coordinate system.

The cylindrical coordinate system is one of many three-dimensional coordinate systems.

This three-dimensional systems includes seven parameters.

A is the area of the primitive surface unit cell and the is the energy per atomic layer in three-dimensional system.

These relations are accurate close to the critical point in two- and three-dimensional systems.

A crystal is a three-dimensional system with translational invariance.