vice.multizone.migration
========================

Type : ``migration.specs``

Default : No migration of either gas or stars.

An object which stores the migration specifications of the multizone
model.

Attributes
----------
gas : ``mig_matrix``
	A matrix describing how gas moves between zones.
stars : <function>
	The migration settings for star particles.

.. seealso::

	- ``vice.multizone.migration.gas``
	- ``vice.multizone.migration.stars``

Example Code
------------
>>> import vice
>>> mz = vice.multizone(name = "example")
>>> mz.migration.gas[1][0] = 0.05
>>> mz.migration.gas[0][1] = 0.05
>>> def f(zone, tform, time):
	'''
	stars born in zone 0 and 1 swap positions when they're more
	than 1 Gyr old.
	'''
	if zone == 0:
		if time - tform > 1:
			return 1
		else:
			return 0
	elif zone == 1:
		if time - tform > 1:
			return 0
		else:
			return 1
	else:
		return zone
>>> mz.migration.stars = f