Compute the square root (for all non-negative numbers).
Accuracy: The result is a tight enclosure.
realsqrt (infsup (-6, 4)) ⇒ ans = [0, 2]
See also: @infsup/sqr, @infsup/rsqrt, @infsup/pow, @infsup/cbrt, @infsup/nthroot.
Package: interval