Setting parameters

    The portion of the script which you might want to edit is after the initial comment section, and looks like this:

###################################################################
# Set up the parameters of the reduction sequences.
# These can be changed to test behaviour of the programs under
# different circumstances.
# The defaults are sensible.  For all the Boolean variables, 
# TRUE is a more resource-intensive option than FALSE.

      # Do we want variances calculated and propagated (TRUE or FALSE)?
            set variance = TRUE

      # Do we want to treat ARD mask within CCDPACK (TRUE or FALSE)?  
      # (else explicitly impose mask on data using ARDMASK).
            set keepard = TRUE

      # Do we want to use a bias frame? (TRUE or FALSE)?
      # (else interpolate between bias strips)
            set biasframe = TRUE

      # Do we want to normalize the frames for scale and zero factors?
            set normalise = TRUE

      # Data type (_WORD, _INTEGER, _REAL or _DOUBLE)
            set datatype = _REAL

      # List of image sizes for frames (pixels along a side)
            set image_sizes = ( 1000 2000 3000 4000 )

      # List of object densities (objects per million pixels).
      # If this is set to ( 0 ) then min_objects will always be used.
            set object_densities = ( 50 )

      # Minimum number of objects per frame (can override object_densities)
            set min_objects = 300

      # Graphic display device ("xwindows" is GWM window, "NONE" is none)
            set device = NONE

      # Set logging interval (seconds)
            set interval = 15

      # Set filename for logging resource usage
            set reslogfile = ccdbig_res.log

# End of parameter setup.
###################################################################

The significance of these options is as follows:

• variance: If set to TRUE then the variance component of the NDFs will be calculated where appropriate (in MAKEBIAS, DEBIAS and MAKEMOS) and propagated. Setting to FALSE decreases memory, disk and CPU time usage.
• keepard: If set to TRUE then the information in the example ARD mask file ccdtest.ard will be used by the CCDPACK applications where appropriate; this increases memory and CPU time usage, especially in DEBIAS. If FALSE, then the ARD mask will be applied explicitly between stages of the reduction process by the KAPPA application ARDMASK.
• biasframe: If set to TRUE then bias frames will be used to debias the images. If FALSE, then the images will be debiassed using interpolation between the bias strips, which means that MAKEBIAS does not need to be run and the demands made by DEBIAS are reduced.
• normalise: Determines whether MAKEMOS performs inter-frame normalisation before combining the images. This is a CPU-intensive step which is not necessary for the synthetic data used by CCDBIG; for real data it may or may not be.
• datatype: This determines the numeric type used to represent the DATA (and VARIANCE, if present) components of the NDFs. This choice is honoured by most parts of the reduction process, but MAKEFLAT always generates a master flat frame of type at least _REAL. The smaller the type the less disk space and I/O resources will be required, but the effect on CPU time requirements is architecture-dependent.
• image_sizes: The data reduction process is performed in turn on test CCD frames of N x N pixels, where N takes each of the values given in this list.
• object_densities: The number of objects generated in the test data can be altered with this value. If more than one number is given, more than one run will be performed at each frame size.
• min_objects: The minimum number of objects (roughly) in a data frame. If too few objects are present then the registration process runs into trouble. If behaviour as a function of number of objects is not being assessed (for most purposes the number of objects is not very important) then object_densities can be set to ( 0 ) and min_objects to some medium sized number for a fixed number of objects regardless of frame size.
• device: This is the graphics device for display. If set to NONE no graphics display is attempted.
• interval: This determines how often the logging process examines the application processes. A smaller value will improve the resolution of the statistics, but will place a heavier load on the system.
• reslogfile: This is the name of the file to which the resource usage summary is logged.