pub fn evaluate(
expression: &str,
lookup: impl FnMut(&str) -> Option<f64>,
) -> GeopResult<f64>Expand description
The value of the formula expression, with lookup the value of each
parameter it names: numbers, + - * / ^, parentheses, pi, and the
functions of FUNCTION_NAMES, with angles in degrees — and, last, one
comparison of two of those, < <= > >= == !=, 1 where it holds and 0
where not: what says whether a step runs, length > 40
(crate::program::ProgramStep::active). Fails for anything else, for
a name lookup does not know, and for a value that is no finite number.