"""
Frame of reference/coordinates package.

Mathematical model:  The idea of a chart S{phi}: I{U} S{sub} I{M} {->} B{R}^k
on a "manifold" I{M}.  For a chart both input (I{M}) and output coordinates
(B{R}^k) must be defined and a map relating the two coordinate systems.
"""

"""
Frame of reference/coordinates package.

Mathematical model:  The idea of a chart S{phi}: I{U} S{sub} I{M} S{->} B{R}^k
on a "manifold" I{M}.  For a chart both input (I{M}) and output coordinates
(B{R}^k) must be defined and a map relating the two coordinate systems.
"""

fix arrow in docstring for epytext markup