calc: Evaluates expressions
calc is a very simple utility for evaluating expressions.
It uses the same expression evaluator as is used in tpipe
and the other generic table tasks for things like creating new columns,
so it can be used as a quick test to see what expressions work,
or in order to evaluate expressions using the various algebraic
functions documented in Section 10.7.
Since usually no table is involved, you can't refer to column names in
the expressions.
It has one mandatory parameter, the expression to evaluate, and writes the
result to the screen.