ARKI Consulting & Development A/S
Versions of CONOPT
The latest version of CONOPT is version 3.10. A letter after 3.10 indicates a bug-fix level.
Version 3.10 is the version currently used with most modeling systems. In GAMS, this version is known as CONOPT3.
To provide compatibility for some old users, GAMS still distributes some older version of CONOPT, version 2.043 and 2.071. Version 2.043, called CONOPT1, does not have the Sequential Linear Programming component and various crash options, and the linear algebra is less efficient for larger models. Version 2.071, called CONOPT2, does not have the Sequential Quadratic Programming component and its scaling option is not as good as in version 3.10. CONOPT1 uses looser tolerances than CONOPT2 so the solutions are in general less accurate.
In general, CONOPT3 should be preferred over the older versions.