**Defined in theory: Simple-geometry****Source code: simple-geometry.lisp**

**Documentation:**A direction cosine matrix is an orthogonal three-dimensional matrix.

**Subclass-Of:**Orthogonal-matrix

**Row-Dimension:**3

(<=> (3d-Direction-Cosine ?Dircos) (And (Orthogonal-Matrix ?Dircos) (Row-Dimension ?Dircos 3)))