Non-linear Duffing equation solution solver. Duffing Measure model computes the solutions to the non-linear Duffing equation, which reads, x'' + 2 x' - x (1 - x2) = f cos( t), where each prime denotes a time derivative. The simulation displays the evolution of a group of oscillators with similar initial parameters on a Poincare plot and the evolution of the oscillator with the central initial parameter displayed on a separate Poincare plot. The evolution parameters can be changed via textboxes. 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.

The upper graphics will display the simultaneous positions and velocities of the N solutions at every time t = 2 n p / ?, for (n = 0, 1, 2,...), i.e., with the frequency of the external force.
In the lower graphics the Poincar?section corresponding to the middle initial conditions will be computed step by step at times t = 2 n p / ?, for (n = n0, n0+1, n0+2,...), where n0 is the numbers of initial cycles to be skipped (this is done to make sure the solution is, approximately, on the attractor).
To change the ranges displayed in each window you may right click on it and use the corresponding menu under the entry called Zoom
For information on other elements, put over them the mouse pointer to get a tooltip.

Requirements:
* Java

The license of this software is Freeware, you can free download and free use this graphing software.