interval, evaluation of f at B using interval arithmetic
Purpose:
computes an interval extension of the polynomial
Example:
LIB "rootisolation.lib";
ring R = 0,(x,y),dp;
poly f = x2+y-1;
box B = list(bounds(-1,1), bounds(1,3)/2);
interval I = evalPolyAtBox(f, B); I;
==> [-1/2, 3/2]