Check if the interval is a common interval, that is a nonemty, closed bounded real interval.
Common intervals are used in class Moore interval arithmetic and are flavor-independent in IEEE Std 1788-2015 interval arithmetic.
Evaluated on interval arrays, this functions is applied element-wise.
See also: @infsup/eq, @infsup/isentire, @infsup/isempty, @infsup/issingleton.
Package: interval