# Common Contexts

Numeric No points, vectors, matrices, complex numbers, or intervals are allowed.
Complex No points, vectors, matrices, or intervals are allowed.
Point Nearly the same as the Vector below, but the angle bracket and ijk notation is not allowed, and vector operations on points are not defined.
Vector The constants i, j, and k are defined as coordinate unit vectors, and vector cross and dot products are allowed. No complex numbers, matrices, or intervals are allowed.
Vector2D Same as Vector above, but i and j are defined as coordinate unit vectors in ${\bf R}^2$, and k is not defined.
Matrix Same as Vector above, but square brackets define matrices instead of points or intervals.
Interval Similar to Numeric context, but (a,b), (a,b], [a,b), and [a,b] create real Intervals rather than lists or errors. Finite sets of reals are created using {a,b,c} (with as many or as few numbers are needed).
Full This context is used to seed the others, and is only intended for internal use. Matrix, vector, point, intervals, and complex numbers all can be created in this context; i is the complex $i$ equal to $\sqrt{-1}$. The variables are x, y, and z.