Custom (User-defined) Display Combinations in SM_GUI

The predefined combinations described above have two limitations:

1. Only calibrated signals can be combined (not raw signals or raw integers)
2. The display combinations have to be defined in the source code, which a regular user is unlikely to be able to do.

Of course, on the IDL command line, you can manipulate your data however you want, but this is quite cumbersome if you require the same combination of channels regularly. Therefore, as of SM_GUI Version 1.4, custom (user-defined) display combinations have been implemented, which allow to combine the different signals (within one signal type) to be combined almost arbitrarily. Note, however, that this only works if the program runs in a fully licensed IDL session, not in the Virtual Machine.

Custom display combinations are defined in the config file (see Sec. 5.20). For each combination you want to define, add a line like

    custom_display "<name>" "<signal type>::<code>"

• <name> is a name you can assign to your liking (it will appear in the Detector / Display dropdown list)

• <signal type> will be either one of Predefined Combinations, Raw Integer, Raw Counts / mVolts or Calibrated kHz. This is not case-sensitive. If you insert an invalid signal type, an error will be raised.

• <code> is a formula which defines the custom combinations. In this formula, you can use all valid signal (detector) names for the chosen signal type (like sidet01, counter, clock etc., again case-insensitive). Basically, you must write a formula which IDL can understand, meaning you can use all standard arithmetic operators ($+$, $-$, $*$, $/$ etc.) and parentheses to group expressions. You can also use numerical constants.

One example for a valid custom display definition would be

    custom_display "sum inner sidet segments (mVolts)" \
        "raw counts / mVolts::sidet01+sidet02+sidet03"

This has been split into two lines because of limited space on the manual page, but in the real config file you must use one line only (omit the backslash).

You can omit the quotes around <name> if there are no space characters in it. Since there will always be a space in the signal type, you can't omit those ones. You can use single quotes if you want.

Once custom display combinations have been defined in the config file (note that you have to restart SM_GUI or do Extra $\rightarrow$ Re-read Config File for the changes to take effect), they are available as a separate signal type if they are valid for the file loaded (see below). For new scans, they don't become available until the scan is finished.