xpp hhh.odewhere I have assumed that you named the file hhh.ode. If everything was typed correctly, a main window and several other windows appear. Three of these other windows are of interest:
Note: If any of the windows appear ``dead'', then iconify them and reopen them. This happens on some window managers.
The Main Windowhas all the menus etc and the one we will work from the most. First, lets change the amount of time to integrate the equations from the default of 20 to 200. Click on nUmerics or tap the letter u. Then choose Total and change it to 200. Type Enter when done. Then type Esc or click on it to return to the main menu.
Click on Initialconds and then Go or tap i g and the equations will be integrated using the default Runge-Kutta integrator. Click on Xi vs t or tap x and accept the default V and then type Enter to plot V(t) in a window that has the entire integration.
In the Initial Data Window, change the initial voltage to -50 and click on Go. In the Main Windowclick on Xi vs t and accept V and type Enter to get the whole voltage trace. Look at the Data Viewerand scroll through the data.
Look at some other variables using the Xi vs t command. Click on Window Window or tap w w and change X hi to 35 to see a better view.
Change the parameter I from 0 to 8 in the parameter window and click on Go. Go back and plot the entire simulation x Enter. There is a periodic solution. Compute the period by holding the mouse button down in the Main Windowwhile moving from peak to peak and observing the (x,y) values in the bottom of the window. The period is about 14 msec.