Behind the scenes

As mentioned earlier, IPE stores the parameters for each program in a file. The format of this parameter file is quite simple; there are many lines of the form ``parameter=value'', where ``parameter'' is the parameter name (also the label on the IPE panel), and ``value'' is the value chosen by the user. Once this is done, IPE uses pipes to construct a single Unix command corresponding to the processing sequence. For the simple ``default'' processing sequence, the command would look like this:

<file Taplot par=parfile.taplot | Ta2vplot par=parfile.ta2vplot 
         | Xvpen par=parfile.xvpen

This command reads in the file ``file'', runs the program ``Taplot'' on it using the parameters located in ``parfile.taplot'', passes the result to the program ``Ta2vplot'', and so on. Finally the result goes to Xvpen, which displays the results on the workstation screen. I could have manually edited these parameter files, then executed this same command myself. But to try out some new parameters, I would have to edit the necessary parameter files and run the job over again. With IPE the result appears on the workstation screen, and I am still editing the parameters on their panels. I can immediately try some new values and see how they change the results.