Find which elements of `a` are equal to at least one element in `b`, to within some tolerance tol.
.in_numeric(a, b, tol = 1e-06)
The vector for which comparison are to be made
The vector to match against.
The tolerance within which values are assumed to be the same.
A vector of logical values the same length as `a` describing whether this vector element is close to at least one element in `b`