Function: rnfeltabstorel
Section: number_fields
C-Name: rnfelementabstorel
Prototype: GG
Help: rnfeltabstorel(rnf,x): transforms the element x from absolute to
 relative 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 modulo the absolute equation
 \kbd{\var{rnf}.pol}, computes $x$ as an element of the relative extension
 $L/K$ as a polmod with polmod coefficients.
