<p>For <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11785_2025_1728_Article_IEq1.gif" Format="GIF" Height="13" Rendition="HTML" Resolution="72" Type="Linedraw" Width="41" /> </InlineMediaObject> <EquationSource Format="TEX">\(a&gt;0\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>a</mi> <mo>&gt;</mo> <mn>0</mn> </mrow> </math></EquationSource> </InlineEquation> and nonnegative integers <i>m</i> and <i>n</i> the classes <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11785_2025_1728_Article_IEq2.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="37" /> </InlineMediaObject> <EquationSource Format="TEX">\(\mathcal {A}^a_{m,n}\)</EquationSource> <EquationSource Format="MATHML"><math> <msubsup> <mrow> <mi mathvariant="script">A</mi> </mrow> <mrow> <mi>m</mi> <mo>,</mo> <mi>n</mi> </mrow> <mi>a</mi> </msubsup> </math></EquationSource> </InlineEquation> of entire functions are introduced. An entire function <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11785_2025_1728_Article_IEq3.gif" Format="GIF" Height="10" Rendition="HTML" Resolution="72" Type="Linedraw" Width="14" /> </InlineMediaObject> <EquationSource Format="TEX">\(\omega \)</EquationSource> <EquationSource Format="MATHML"><math> <mi>ω</mi> </math></EquationSource> </InlineEquation> belongs to <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11785_2025_1728_Article_IEq2.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="37" /> </InlineMediaObject> <EquationSource Format="TEX">\(\mathcal {A}^a_{m,n}\)</EquationSource> <EquationSource Format="MATHML"><math> <msubsup> <mrow> <mi mathvariant="script">A</mi> </mrow> <mrow> <mi>m</mi> <mo>,</mo> <mi>n</mi> </mrow> <mi>a</mi> </msubsup> </math></EquationSource> </InlineEquation> if <InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11785_2025_1728_Article_IEq3.gif" Format="GIF" Height="10" Rendition="HTML" Resolution="72" Type="Linedraw" Width="14" /> </InlineMediaObject> <EquationSource Format="TEX">\(\omega \)</EquationSource> <EquationSource Format="MATHML"><math> <mi>ω</mi> </math></EquationSource> </InlineEquation> is real on the imaginary axis and has the form <InlineEquation ID="IEq6"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11785_2025_1728_Article_IEq6.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="376" /> </InlineMediaObject> <EquationSource Format="TEX">\((i\mu )^{n-m+1}\omega (\mu ) =\chi _1(\mu )\cos \mu a+ i\chi _2(\mu )\sin \mu a+\Psi (\mu )\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msup> <mrow> <mo stretchy="false">(</mo> <mi>i</mi> <mi>μ</mi> <mo stretchy="false">)</mo> </mrow> <mrow> <mi>n</mi> <mo>-</mo> <mi>m</mi> <mo>+</mo> <mn>1</mn> </mrow> </msup> <mi>ω</mi> <mrow> <mo stretchy="false">(</mo> <mi>μ</mi> <mo stretchy="false">)</mo> </mrow> <mo>=</mo> <msub> <mi>χ</mi> <mn>1</mn> </msub> <mrow> <mo stretchy="false">(</mo> <mi>μ</mi> <mo stretchy="false">)</mo> </mrow> <mo>cos</mo> <mi>μ</mi> <mi>a</mi> <mo>+</mo> <mi>i</mi> <msub> <mi>χ</mi> <mn>2</mn> </msub> <mrow> <mo stretchy="false">(</mo> <mi>μ</mi> <mo stretchy="false">)</mo> </mrow> <mo>sin</mo> <mi>μ</mi> <mi>a</mi> <mo>+</mo> <mi mathvariant="normal">Ψ</mi> <mrow> <mo stretchy="false">(</mo> <mi>μ</mi> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation>, where <InlineEquation ID="IEq7"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11785_2025_1728_Article_IEq7.gif" Format="GIF" Height="12" Rendition="HTML" Resolution="72" Type="Linedraw" Width="19" /> </InlineMediaObject> <EquationSource Format="TEX">\(\chi _1\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>χ</mi> <mn>1</mn> </msub> </math></EquationSource> </InlineEquation> is a polynomial of degree <InlineEquation ID="IEq8"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11785_2025_1728_Article_IEq8.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="40" /> </InlineMediaObject> <EquationSource Format="TEX">\(n+1\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>n</mi> <mo>+</mo> <mn>1</mn> </mrow> </math></EquationSource> </InlineEquation> with leading coefficient <InlineEquation ID="IEq9"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11785_2025_1728_Article_IEq9.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="29" /> </InlineMediaObject> <EquationSource Format="TEX">\(i^{n+1}\)</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mi>i</mi> <mrow> <mi>n</mi> <mo>+</mo> <mn>1</mn> </mrow> </msup> </math></EquationSource> </InlineEquation>, <InlineEquation ID="IEq10"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11785_2025_1728_Article_IEq10.gif" Format="GIF" Height="12" Rendition="HTML" Resolution="72" Type="Linedraw" Width="19" /> </InlineMediaObject> <EquationSource Format="TEX">\(\chi _2\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>χ</mi> <mn>2</mn> </msub> </math></EquationSource> </InlineEquation> is a polynomial of degree at most <i>n</i>, and <InlineEquation ID="IEq11"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11785_2025_1728_Article_IEq11.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="14" /> </InlineMediaObject> <EquationSource Format="TEX">\(\Psi \)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">Ψ</mi> </math></EquationSource> </InlineEquation> is small with respect to the other terms. When <InlineEquation ID="IEq12"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11785_2025_1728_Article_IEq12.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="46" /> </InlineMediaObject> <EquationSource Format="TEX">\(m=0\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>m</mi> <mo>=</mo> <mn>0</mn> </mrow> </math></EquationSource> </InlineEquation>, these functions are sine type functions. The functions in <InlineEquation ID="IEq13"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11785_2025_1728_Article_IEq2.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="37" /> </InlineMediaObject> <EquationSource Format="TEX">\(\mathcal {A}^a_{m,n}\)</EquationSource> <EquationSource Format="MATHML"><math> <msubsup> <mrow> <mi mathvariant="script">A</mi> </mrow> <mrow> <mi>m</mi> <mo>,</mo> <mi>n</mi> </mrow> <mi>a</mi> </msubsup> </math></EquationSource> </InlineEquation> have infinitely many zeros with explicitly given asymptotic behaviour, for which the first <InlineEquation ID="IEq14"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11785_2025_1728_Article_IEq8.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="40" /> </InlineMediaObject> <EquationSource Format="TEX">\(n+1\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>n</mi> <mo>+</mo> <mn>1</mn> </mrow> </math></EquationSource> </InlineEquation> terms in the asymptotics are determined by the coefficients in the polynomials <InlineEquation ID="IEq15"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11785_2025_1728_Article_IEq7.gif" Format="GIF" Height="12" Rendition="HTML" Resolution="72" Type="Linedraw" Width="19" /> </InlineMediaObject> <EquationSource Format="TEX">\(\chi _1\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>χ</mi> <mn>1</mn> </msub> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq16"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11785_2025_1728_Article_IEq10.gif" Format="GIF" Height="12" Rendition="HTML" Resolution="72" Type="Linedraw" Width="19" /> </InlineMediaObject> <EquationSource Format="TEX">\(\chi _2\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>χ</mi> <mn>2</mn> </msub> </math></EquationSource> </InlineEquation>. Conversely, any sequence of complex numbers with such an asymptotic representation determines a unique function from a class <InlineEquation ID="IEq17"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11785_2025_1728_Article_IEq2.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="37" /> </InlineMediaObject> <EquationSource Format="TEX">\(\mathcal {A}^a_{m,n}\)</EquationSource> <EquationSource Format="MATHML"><math> <msubsup> <mrow> <mi mathvariant="script">A</mi> </mrow> <mrow> <mi>m</mi> <mo>,</mo> <mi>n</mi> </mrow> <mi>a</mi> </msubsup> </math></EquationSource> </InlineEquation> whose zeros are this given sequence. Some explicit formulas for the direct and the inverse problem are provided.</p>

错误:搜索内容不能为空,请输入英文关键词
错误:关键词超出字数限制,请精简
高级检索

The Direct and Inverse Problem for a Class of Entire Functions Related to Sine Type Functions

  • Manfred Möller

摘要

For \(a>0\) a > 0 and nonnegative integers m and n the classes \(\mathcal {A}^a_{m,n}\) A m , n a of entire functions are introduced. An entire function \(\omega \) ω belongs to \(\mathcal {A}^a_{m,n}\) A m , n a if \(\omega \) ω is real on the imaginary axis and has the form \((i\mu )^{n-m+1}\omega (\mu ) =\chi _1(\mu )\cos \mu a+ i\chi _2(\mu )\sin \mu a+\Psi (\mu )\) ( i μ ) n - m + 1 ω ( μ ) = χ 1 ( μ ) cos μ a + i χ 2 ( μ ) sin μ a + Ψ ( μ ) , where \(\chi _1\) χ 1 is a polynomial of degree \(n+1\) n + 1 with leading coefficient \(i^{n+1}\) i n + 1 , \(\chi _2\) χ 2 is a polynomial of degree at most n, and \(\Psi \) Ψ is small with respect to the other terms. When \(m=0\) m = 0 , these functions are sine type functions. The functions in \(\mathcal {A}^a_{m,n}\) A m , n a have infinitely many zeros with explicitly given asymptotic behaviour, for which the first \(n+1\) n + 1 terms in the asymptotics are determined by the coefficients in the polynomials \(\chi _1\) χ 1 and \(\chi _2\) χ 2 . Conversely, any sequence of complex numbers with such an asymptotic representation determines a unique function from a class \(\mathcal {A}^a_{m,n}\) A m , n a whose zeros are this given sequence. Some explicit formulas for the direct and the inverse problem are provided.