Singular Manual: allrealst

| #### D.12.7.7 allrealst Procedure from library `rootsur.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 Example:
    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
See also: allreal; sturm; sturmha.

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