The Fortran subroutine NLPQLP, a newer^[when?] version of NLPQL, solves smooth nonlinear programming problems by a sequential quadratic programming (SQP) algorithm. The new version is specifically tuned to run under distributed systems. In case of computational errors, such as inaccurate function or gradient evaluations, a non-monotone line search is activated. The code is easily transformed to C by f2c and is widely used in academia and industry.

• Schittkowski, Klaus (2014), "NLPQLP: A Fortran Implementation of a Sequential Quadratic Programming Algorithm with Distributed and Non-Monotone Line Search", Report

• http://klaus-schittkowski.de/nlpqlp.htm
• https://www.schittkowski.de/numericalsoftware_nlpqlp.php