### SCUBA2_DISPLAY_PCA

Calculate and display properties of PCA components

#### Description:

Apply PCA processing to raw SCUBA-2 data to determine dominant modes.

The input data should contain a fast-ramp flatfield (taken prior to the target data).

#### Notes:

• Input files must contain raw SCUBA-2 data.

• Input data should be from a single subarray only, and for a single observation. However, no checks are made that this is actually the case.

• If results are to be calculated by the recipe, then all the input data are used. This could lead to long run times with a large number of files as the data are pre-processed with SMURF sc2clean.

#### Available Parameters :

##### LOGFILE
Flag to denote whether to write results to a log file at the end of processing. Default is 1 (write a log file).
##### PCA_COMP
PCA components to analyze and display. Default is 0 to 5. The components may be specified either as a comma-separated list (e.g. 0,1,2,3 etc - they need not be contiguous or in order), or as a Perl array slice (e.g. 0..3). The number of components must be no more than 8. If more than 8 are given, only the first 8 are used.
##### PCA_KEEPFILES
Flag to indicate which files should be kept on disk. Default is 1 which keeps the PCA amplitude, component and power spectrum files on disk. A value of 0 deletes all files, while a value of
• 1 indicates that all files should be kept on disk.

##### PCA_REUSE
Flag to indicate that existing data should be used if present. Default is 1 (reuse).

#### Display

The results for each chosen PCA component are displayed in up to two KAPVIEW windows. The left-hand column displays the amplitude scaled between $+$/-2 sigma, the next column displays the component as a function of time and the third column shows the power spectrum of each component. Each KAPVIEW window can display results for up to 4 PCA components.