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D.12.8.6 boundDes

Procedure from library rootsur.lib (see rootsur_lib).

Usage:
boundDes(p); poly p

Return:
int: an upper bound for the number of real roots of p, with the same parity as the actual number of real roots of p.

Assume:
p is a univariate polynomial with rational coefficients

Example:
 
LIB "rootsur.lib";
ring r = 0,x,dp;
poly p = (x+2)*(x-1)*(x-5);
boundDes(p);
==> 3
p = p*(x2+1);
boundDes(p);
==> 5
See also: boundBuFou.