LGS 2D 3.0 Since version 3.0 LGS2D solver provides built-in class of curves with modifiable shape – NURBS curves, which are commonly used in CAD applications. Their usage in LGS doesn’t require callback functions implementation – all information is provided during creation. Thus, creation of NURBS is as easy as creation of lines or circles. Besides, using built-in curves in solver leads to significant performance improvement, since the derivatives of a NUBRS evaluation function needed for numerical methods are now computed analytically inside the solver. To test NURBS curves in Legend demo application, you can set an option “Enable NURBS support” in “Solver” menu. With that flag activated legend splines will be modeled in LGS as build-in NURBS curves. With this flag turned off, the same spline curves will be implemented as user-defined dependent curves, using callback. Thus, by turning this flag on and off you can compare gain in performance (which is especially noticeable when using move underconstrained functionality). Simple example below demonstrates modeling the profile of plane wing using NURBS. Firstly, tangency constraint is set between two curves to make their connection smooth. Then, moving under constraint functionality is demonstrated. Finally, shape of the profile is modified by changing lengths of several edges.