Return the mantissa and exponent of x, as pair (m, e). m is a float and e is an int, such that x = m * 2.**e. If x is 0, m and e are both 0. Else 0.5 <= abs(m) < 1.0. This is a function tag. This is a filter tag.
Check if float x is infinite (positive or negative). This is a comparison tag.
Check if float x is not a number (NaN). This is a comparison tag.