This program can be used to analyse truss structure(like 'link180 in Ansys').
A truss structure consist of nodes and struts.the "InputData" show the format of this structure.
Before analysing,external forces and node constraints must be set.

And the results of this program are almost same as Ansys.
There are two pictures show results of this program(running in a GUI environment)
and results of Ansys.

Use Finite Element Method to analyse Truss structure.
Use Eigen to Solve the Sparse Matrix.
Eigen:http://eigen.tuxfamily.org/index.php?title=Main_Page