Major Section: PROGRAMMING
(Expt r i) is the result of raising the number r to the
integer power i.
The guard for (expt r i) is that r is a number and i
is an integer, and furthermore, if r is 0 then i is
nonnegative. When the type requirements of the guard aren't
met, (expt r i) first coerces r to a number and i to an
integer.
Expt is a Common Lisp function. See any Common Lisp
documentation for more information. Note that r can be a complex
number; this is consistent with Common lisp.