Function: rnfeltreltoabs
Section: number_fields
C-Name: rnfeltreltoabs
Prototype: GG
Help: rnfeltreltoabs(rnf,x): transforms the element x from relative to
 absolute representation.
Doc: $\var{rnf}$ being a relative
 number field extension $L/K$ as output by \kbd{rnfinit} and $x$ being an
 element of $L$ expressed as a polynomial or polmod with polmod
 coefficients, computes $x$ as an element of the absolute extension $L/\Q$ as
 a polynomial modulo the absolute equation \kbd{\var{rnf}.polabs}.
 \bprog
 ? K = nfinit(y^2+1); L = rnfinit(K, x^2-y);
 ? L.polabs
 %2 = x^4 + 1
 ? rnfeltreltoabs(L, Mod(x, L.pol))
 %3 = Mod(x, x^4 + 1)
 ? rnfeltreltoabs(L, Mod(y, x^2-y))
 %4 = Mod(x^2, x^4 + 1)
 ? rnfeltreltoabs(L, Mod(y,K.pol))
 %5 = Mod(x^2, x^4 + 1)
 @eprog\noindent If the input is actually rational, then \kbd{rnfeltreltoabs}
 returns it as a rational number instead of a \typ{POLMOD}:
 \bprog
 ? rnfeltreltoabs(L, Mod(2, K.pol))
 %6 = 2
 @eprog
