Function: idealispower
Section: number_fields
C-Name: idealispower
Prototype: lGGLD&
Help: idealispower(nf,A,n,{&B}): return 1 if A = B^n is an n-th power
 else return 0.
Doc: let \var{nf} be a number field and $n > 0$ be a positive integer.
 Return $1$ if the fractional ideal $A = B^{n}$ is an $n$-th power and $0$
 otherwise. If the argument $B$ is present, set it to the $n$-th root of $A$,
 in HNF.
 \bprog
 ? K = nfinit(x^3 - 2);
 ? A = [46875, 30966, 9573; 0, 3, 0; 0, 0, 3];
 ? idealispower(K, A, 3, &B)
 %3 = 1
 ? B
 %4 =
 [75 22 41]

 [ 0  1  0]

 [ 0  0  1]

 ? A = [9375, 2841, 198; 0, 3, 0; 0, 0, 3];
 ? idealispower(K, A, 3)
 %5 = 0
 @eprog\noindent
