  We have developed a software library for chemical evolution simulations of
galaxy formation under the simple stellar population (SSP) approximation. In
this library, all of the necessary components concerning chemical evolution,
such as initial mass functions, stellar lifetimes, yields from type II and Ia
supernovae, asymptotic giant branch stars, and neutron star mergers, are
compiled from the literature. Various models are pre-implemented in this
library so that users can choose their favorite combination of models.
Subroutines of this library return released energy and masses of individual
elements depending on a given event type. Since the redistribution manner of
these quantities depends on the implementation of users' simulation codes, this
library leaves it up to the simulation code. As demonstrations, we carry out
both one-zone, closed box simulations and three-dimensional simulations of a
collapsing gas and dark matter system using this library. In these simulations,
we can easily compare the impact of individual models on the chemical evolution
of galaxies, just by changing the control flags and parameters of the library.
Since this library only deals with the part of chemical evolution under the SSP
approximation, any simulation codes that use the SSP approximation -- namely
particle-base and mesh codes, as well as semi-analytical models -- can use it.
This library is named "CELib" after the term "Chemical Evolution Library" and
is made available to the community.
