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D.12.8.7 allrealst
Procedure from libraryrootsur.lib (see rootsur_lib).
- Usage:
- allrealst(p); poly p
- Return:
- int: 1 if and only if all the roots of p are real, 0 otherwise.
Checks by using Sturm's Theorem whether all the roots of p are real
- Assume:
- p is a univariate polynomial with rational coefficients
LIB "rootsur.lib"; ring r = 0,x,dp; poly p = (x+2)*(x-1)*(x-5); allrealst(p); ==> 1 p = p*(x2+1); allrealst(p); ==> 0 |