\chapter{{\tt Ideq}: Integer Dequeue}
\par
The {\tt Ideq} is a object that manages a {\it dequeue},
a list data structure that supports inserts and deletes
at both the head and the tail of the list.
We wrote this application in support of a max flow code
where visiting an out-edge put a vertex on the head of the list
and visiting an in-edge put a vertex on the tail of the list.
The goal was to be close to a depth first traversal of the network.
This object is also used in multithreaded and MPI factorizations
and forward and back solves, where each process must perform a
bottom-up or top-down traversal of a tree.
The {\tt Ideq} object is used to specify which nodes of the tree to
visit (possibly repeatedly) in which order.
\par
The dequeue has fixed size though it can grow using the
{\tt Ideq\_resize()} method.
\par
