OpenOpt is cross-platform (Windows, Linux, Mac OS etc) Python-written framework. If you have a model written in FuncDesigner (http:// openopt.org/FuncDesigner), you can get 1st derivatives via automatic differentiation (http://en.wikipedia.org/wiki/ Automatic_differentiation) (some examples here: http://openopt.org/NumericalOptimizationForFuncDesignerModels). License BSD allows to use it in both open- and closed-code soft. For more details see http://openopt.org/ http://forum.openopt.org/viewtopic.php?id=141 Regards, D.