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CountRoots

CountRoots[poly, x]
gives the number of real roots of the polynomial poly in x.
CountRoots[poly, {x, a, b}]
gives the number of roots between a and b.
  • CountRoots enumerates roots with multiplicities counted.
  • Roots that lie exactly at x=a or x=b are counted.
  • The limits a and b can be complex, in which case the range is taken to be a closed rectangle in the complex plane.
New in 6