Changes
The PyPlot window has a number of controls that let you change the settings of your graph using your mouse. For example, using the Pan/Zoom button [[Image:Py_zoom_icon.png]], you can pan the graph with the left mouse button and zoom it in or out with the right mouse button. A combination of the two operations usually gives you an ideal scaling of your graph. As you move the mouse on the graph, you can read the value of the horizontal axis (X) and the corresponding value of the total electric field distribution along the X direction.
The distance between two consecutive field maxima is equivalent to &lambda:;<sub>g</sub>/2. First click on the [[Image:Py_zoom_icon.png]] button to get an enlarged view of middle position of the graph. Move the mouse to the top of one of the field maxima in the graph and read the values on the lower right corner of the status bar, in this case 0.24590,1467.72). Then move the mouse to the next field maximum and read the values (6.14754,1468.81). You will see Δx = 5.9mm., which is equal to half the calculated guide wavelength.
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