Function: idealappr
Section: number_fields
C-Name: idealappr0
Prototype: GGD0,L,
Help: idealappr(nf,x,{flag=0}): x being a fractional ideal, gives an element
 b such that v_p(b)=v_p(x) for all prime ideals p dividing x, and v_p(b)>=0
 for all other p. If (optional) flag is non-null x must be a prime ideal
 factorization with possibly zero exponents

