vice.milkyway.default_evolution
===============================

The default evolutionary function of the ``milkyway`` object.

**Signature**: vice.milkyway.default_evolution(radius, time)

Parameters
----------
radius : float
	Galactocentric radius in kpc.
time : float
	Simulation time in Gyr.

Returns
-------
value : float
	Always returns the value of 1.0. The interpretation of this is set
	by the attribute ``mode``. With the default value of "ifr", this
	represents a uniform surface of infall of 1.0
	:math:`M_\odot yr^{-1} kpc^{-2}`.

Example Code
------------
>>> import vice
>>> mw = vice.milkyway(name = "example")
>>> mw.evolution
<function vice.milkyway.milkyway.milkyway.default_evolution(radius, time)>
>>> vice.milkyway.default_evolution(10, 1)
1.0
>>> vice.milkyway.default_evolution(5, 4)
1.0