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### B.2.1 Usage

The usage of `calc` is

       stilts <stilts-flags> calc table=<table>
                                  [expression=]<expr>

If you don't have the `stilts` script installed, write "`java -jar stilts.jar`" instead of "`stilts`" - see Section 3. The available `<stilts-flags>` are listed in Section 2.1. For programmatic invocation, the Task class for this command is `uk.ac.starlink.ttools.task.Calc`.

Parameter values are assigned on the command line as explained in Section 2.3. They are as follows:

`expression = <expr>` (String)
  An expression to evaluate. The functions in Section 10.7 can be used.
`table = <table>` (StarTable)
  A table which provides the context within which `expression` is evaluated. This parameter is optional, and will usually not be required; its only purpose is to allow use of constant expressions (table parameters) associated with the table. These can be referenced using identifiers of the form `param$*`, `ucd$*` or `utype$*` - see Section 10.2 for more detail.

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STILTS - Starlink Tables Infrastructure Library Tool Set
Starlink User Note256
STILTS web page: http://www.starlink.ac.uk/stilts/
Author email: m.b.taylor@bristol.ac.uk
Mailing list: topcat-user@jiscmail.ac.uk