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D.12.7.10 sturm

Procedure from library rootsur.lib (see rootsur_lib).

Usage:
sturm(p,a,b); poly p, number a,b

Return:
int: the number of real roots of p in (a,b]

Assume:
p is a univariate polynomial with rational coefficients,
a, b are rational numbers with a < b

Example:
 
LIB "rootsur.lib";
ring r = 0,x,dp;
poly p = (x+2)*(x-1)*(x-5);
sturm(p,-3,6);
==> 3
p = p*(x2+1);
sturm(p,-3,6);
==> 3
p = p*(x+2);
sturm(p,-3,6);
==> 3
See also: allreal; allrealst; sturmha.