Other active devices, e.g. diodes and transistors, might follow one day. At this point, if one or more components lacks a value, you will be invited to supply as many values as are required. The component whose value you are being asked to enter turns red, so you know which one the program is talking about. Once all components have been given values, the program analyses the circuit and computes the voltages at each node. When the computations are complete, a number of graphs will appear.
Voltmeters measure complex voltages, and the graphs show the magnitude in red and the phase in blue.
The graphs are produced with the help of the excellent gd GIF manipulation library from Quest Protein Database Center. A table of complex voltages at each node, for various values of frequency, is also given. This is a teaching tool. It's not finished. The error messages are sometimes not helpful.