The type for points.

dim is the dimension of points of type t.

The type for matrices representing linear transformations of homogenous dim space.

o is the point whose coordinates are all zero.

mid p q is the mid point (p + q)/2.

tr m p is the affine transform in homogenous dim space of the point p by m.

Note. Since m is supposed to be affine the function ignores the last row of m. p is treated as a finite point (its last coordinate in homogenous space is 1).