27.12.6  Similarity in space

See Section 26.14.6 for similarities in the plane.

The similarity command creates a command to rotate and scale about a given line.

• similarity takes three mandatory arguments and one optional argument:
  • L, a line (the axis of the rotation).
  • r, a real number (the scaling ratio).
  • θ, a real number (the angle of rotation).
  • Optionally, G, a geometric object.
• similarity(L,r,θ) returns a new command which rotates about L through an angle of θ and scales about L by a factor of r. If r is negative, the direction of rotation is reversed.
• similarity(L,r,θ,G) returns and draws the transformation of G.

Examples