√ — Root√Y: square root. Pervasive. Perfect roots of exact values stay exact.
√9 ¯4 ⍝ 3 0j2
√1r9 ⍝ 1r3
X√Y: principal Xth root. Negative real Y with odd integral X uses the real root. Negative degrees reciprocate.
3√¯8 ⍝ ¯2
¯3x√¯8x ⍝ ¯1r2
2√3j4 ⍝ 2j1
DOMAIN: zero or infinite degree; zero with a negative real degree.