octant

The coordinate planes ($yz$-plane, $zx$-plane, $xy$-plane) the space ${ℝ}^3$ into eight trihedral angles, which are called the octants of the space.  The magnitude of each octant as a solid angle is $\frac{\pi }{2}$.

Any coordinate of a point moving in a certain octant preserves its sign (http://planetmath.org/SignumFunction).  One calls the octant, where all three coordinates are nonnegative, the first octant.  The other octants have no agreed numbering; see still http://de.wikipedia.org/wiki/Oktant_(Geometrie)Wikipedia.

Title	octant
Canonical name	Octant
Date of creation	2013-03-22 18:51:53
Last modified on	2013-03-22 18:51:53
Owner	pahio (2872)
Last modified by	pahio (2872)
Numerical id	5
Author	pahio (2872)
Entry type	Definition
Classification	msc 51N20
Related topic	Quadrant
Defines	first octant