<p>We localize the zeros of complex harmonic trinomials <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(r_\alpha (z)=z^k+\frac{\alpha }{\overline{z}^\ell }-1\)</EquationSource> </InlineEquation>, where <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(k, \ell \in {\mathbb {N}}\)</EquationSource> </InlineEquation>, <InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(k&gt;\ell \)</EquationSource> </InlineEquation> with <InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(\gcd (k,\ell )=1\)</EquationSource> </InlineEquation>. We prove that for <InlineEquation ID="IEq5"> <EquationSource Format="TEX">\(|\alpha |&lt;\left( \frac{\ell }{k+\ell }\right) ^\frac{\ell }{k}\left( \frac{k}{k+\ell }\right) \)</EquationSource> </InlineEquation>, <InlineEquation ID="IEq6"> <EquationSource Format="TEX">\(r_\alpha \)</EquationSource> </InlineEquation> has <i>k</i> and <InlineEquation ID="IEq7"> <EquationSource Format="TEX">\(\ell \)</EquationSource> </InlineEquation> number of sense-preserving and sense-reversing zeros, respectively. However, <InlineEquation ID="IEq8"> <EquationSource Format="TEX">\(r_\alpha \)</EquationSource> </InlineEquation> has only <InlineEquation ID="IEq9"> <EquationSource Format="TEX">\((k-\ell )\)</EquationSource> </InlineEquation> sense-preserving zeros for <InlineEquation ID="IEq10"> <EquationSource Format="TEX">\(|\alpha |&gt;\left( \frac{\ell }{k-\ell }\right) ^\frac{\ell }{k}\left( \frac{k}{k-\ell }\right). \)</EquationSource> </InlineEquation> For certain choices of the parameter <InlineEquation ID="IEq11"> <EquationSource Format="TEX">\(\alpha \)</EquationSource> </InlineEquation>, we obtain distinct annular sectors each containing exactly one non-singular zero of <InlineEquation ID="IEq12"> <EquationSource Format="TEX">\(r_\alpha \)</EquationSource> </InlineEquation>. Also, we provide zero-exclusion regions and pictorial demonstrations for certain <InlineEquation ID="IEq13"> <EquationSource Format="TEX">\(r_\alpha \)</EquationSource> </InlineEquation>.</p>

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Location of the zeros of harmonic rational trinomials

  • Adithya Mayya,
  • Sarika Verma,
  • Raj Kumar

摘要

We localize the zeros of complex harmonic trinomials \(r_\alpha (z)=z^k+\frac{\alpha }{\overline{z}^\ell }-1\) , where \(k, \ell \in {\mathbb {N}}\) , \(k>\ell \) with \(\gcd (k,\ell )=1\) . We prove that for \(|\alpha |<\left( \frac{\ell }{k+\ell }\right) ^\frac{\ell }{k}\left( \frac{k}{k+\ell }\right) \) , \(r_\alpha \) has k and \(\ell \) number of sense-preserving and sense-reversing zeros, respectively. However, \(r_\alpha \) has only \((k-\ell )\) sense-preserving zeros for \(|\alpha |>\left( \frac{\ell }{k-\ell }\right) ^\frac{\ell }{k}\left( \frac{k}{k-\ell }\right). \) For certain choices of the parameter \(\alpha \) , we obtain distinct annular sectors each containing exactly one non-singular zero of \(r_\alpha \) . Also, we provide zero-exclusion regions and pictorial demonstrations for certain \(r_\alpha \) .