To continue natural extension of the code and allow easy addition of new features, IBM Research decided to invest in an open source re-write of IPOPT in C++. With the help of Carl Laird, who came to the Mathematical Sciences Department at IBM Research as a summer intern in 2004 and 2005 during his PhD studies, the code was re-implemented from scratch.
The new C++ version of the IPOPT optimization code (IPOPT 3.0.0
and beyond) is maintained at IBM Research and remains part of the
COIN-OR initiative. The development on the Fortran version has
ceased, but the source code can still be downloaded from