given a Polynomial or a trigonometric Polynomial(adsbygoogle = window.adsbygoogle || []).push({});

[tex] K(z)= \sum_{n=0}^{N}a_{n}x^{n} [/tex] and

[tex] H(x)= \sum_{n=0}^{N}b_{n}e^{inx} [/tex]

is there a criterion to decide or to see if K(z) or H(x) have ONLY real roots

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# Real roots criterion

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