The Ejs Action for the Harmonic Oscillator model displays the trajectory of a simple harmonic oscillator by minimizing the classical action.  The simulation displays the endpoints of the motion (t,x) which can be changed by using the text boxes or dragging, and displays the new trajectory as well as calculates the physical trajectory (that minimizes the action).  You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting "Open Ejs Model" from the pop-up menu item.  

Ejs Action for the Harmonic Oscillator model was created using the Easy Java Simulations (Ejs) modeling tool.  It is distributed as a ready-to-run (compiled) Java archive.  Double clicking the ejs_ehu_analytical_mechanics_action.jar file will run the program if Java is installed.  Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models.  Additional Ejs models for classical mechanics are available.  They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Please note that this resource requires at least version 1.5 of Java (JRE).