Function: dirpowers
Section: linear_algebra
C-Name: dirpowers
Prototype: LGp
Help: dirpowers(n,x): return the vector [1^x,2^x,...,n^x].
Doc: for nonnegative $n$ and complex number $x$, return the vector with $n$
 components $[1^{x},2^{x},\dots,n^{x}]$.
 \bprog
 ? dirpowers(5, 2)
 %1 = [1, 4, 9, 16, 25]
 ? dirpowers(5, 1/2)
 %2 = [1, 1.414..., 1.732..., 2.000..., 2.236...]
 @eprog\noindent When $n \le 0$, the function returns the empty vector \kbd{[]}.
