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D.12.7.4 boundBuFou
Procedure from library rootsur.lib (see rootsur_lib).
- Usage:
- boundBuFou(p,a,b); p poly, a,b number
- Return:
- int: an upper bound for the number of real roots of p in (a,b],
with the same parity as the actual number of roots (using the
Budan-Fourier Theorem)
- 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);
boundBuFou(p,-3,5);
==> 3
boundBuFou(p,-2,5);
==> 2
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See also:
boundposDes;
varsigns.
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