10 Parameter behaviour and control

CCDPACK has a number of ‘global’ program parameters which you can set up ‘once and for all’2. The usual time to do this is at the beginning of a reduction sequence. Global parameters are used (when set) to override all other values (typically the current values of other applications or perhaps dynamically generated defaults). The global values may be overridden, at any time by values entered on the command line, or given in response to a prompt. The program which sets up the global parameters is:

• CCDSETUP

This routine is described in §7.1.1.

The current values of the global parameters can be viewed at any time by using the routine:

The global values should always be cleared before analysing data from a different instrument, this is achieved using:

Which can also clear individual parameters.

A second control strategy that CCDPACK routines use is that of leaving parameters set at the last used value (this is known as the ‘current’ value). This means that once a parameter has a value assigned to it (by a run of an application) this will be used again, unless it’s one of those with a global association, which if set will override this, or one whose effect is judged so critical that you’d better ask for it on each occasion of use. This general principle is useful in that you do not have to remember to set most parameters every time you run an application. However, this does have a drawback that you must remember what value you gave to the parameter. Most parameters will appear in the log or be directly reported (if the log system is set up to do so), so always take care to inspect the log, or the terminal output, until you’re sure of how things are set up. To get rid of any unwanted parameter values (and restore the ‘intrinsic’ default behaviour of an application) just use the keyword RESET, on the command line (this is used in many of the examples shown in this document for just this purpose). This clears all current values but does not effect the global parameters.

If resetting the parameters seems not to work or you want to clear all the CCDPACK current values, then a brutal reset can be achieved by deleting the appropriate files (application_name.sdf) in the $HOME/adam or $ADAM_USER directories. If you’re using CCDPACK from ICL then the parameter values are kept in the files – ccdpack_red.sdf, ccdpack_reg.sdf and ccdpack_res.sdf. The global parameters are always kept in GLOBAL.sdf.

2This section does not apply to XREDUCE or IRAF.