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If the separator symbol is pred
, the result of the formula is
treated as a true/false value; calc-eval
returns t
or
nil
, respectively. A value is considered "true" if it is a
non-zero number, or false if it is zero or if it is not a number.
For example, `(calc-eval "$<$$" 'pred a b)' tests whether one value is less than another.
As usual, it is also possible for calc-eval
to return one of
the error indicators described above. Lisp will interpret such an
indicator as "true" if you don't check for it explicitly. If you
wish to have an error register as "false", use something like
`(eq (calc-eval ...) t)'.
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