Function: idealchinese
Section: number_fields
C-Name: idealchinese
Prototype: GGG
Help: idealchinese(nf,x,y): x being a prime ideal factorization and y a
 vector of elements, gives an element b such that v_p(b-y_p)>=v_p(x) for all
 prime ideals p dividing x, and v_p(b)>=0 for all other p

