Allowing elements to be arbitrarily included or excluded from fitting and other operations is a very powerful facility which allows much flexibility in the data analysis process. ``Bad'' data points can be excluded from operations. Optimum non-rectangular data regions can be selected reducing calculations for fitting and other calculation intensive operations.
The ``mask'' is a 2-D area of the same size as the current data and memory
arrays. Each data element may be ``masked'' or not. By default
no elements are masked. The command DEFINE MASK (See
Section 17.8, Page )
allows masked-off regions to be defined, and the command
INPUT PARAMETERS (See Section 17.11,
Page
) also calls the DEFINE MASK
routine. The command CLEAR MASK (See Section 17.5,
Page
) resets all elements to ``unmasked''.
Alternatively the ``masked-off'' areas can be defined from the data
values themselves by using the THRESHOLD MASKING command. This
allows a threshold value to be defined and all data elements with values
above, or below (as required), this value are defined as ``masked-off''
(see Section 17.25,
Page ).
The mask can be ``transferred'' to the memory for further use and
possible storage using the TRANSFER MASK TO MEMORY command
(see Section 17.27,
Page
).