Raise x to a power
x xexp y xexp[x;y]
Where x and y are numerics, returns as a float where x is
x
y
0n
q)2 xexp 8 256f q)-2 2 xexp .5 0n 1.414214 q)1.5 xexp -4.2 0 0.1 0n 0w 0.1821448 1 1.04138 0n 0w