<p>This study begins by examining the monotonic behavior of the function <InlineEquation ID="IEq1"> <EquationSource Format="MATHML"><math> <mo>ln</mo> <mi mathvariant="normal">Γ</mi> <mo stretchy="false">(</mo> <mi>x</mi> <mo>+</mo> <mn>1</mn> <mo stretchy="false">)</mo> <mo stretchy="false">/</mo> <mrow> <mo>(</mo> <mo>ln</mo> <mrow> <mo>(</mo> <msup> <mi>x</mi> <mn>2</mn> </msup> <mo>+</mo> <mn>6</mn> <mo>)</mo> </mrow> <mo>−</mo> <mo>ln</mo> <mo stretchy="false">(</mo> <mi>x</mi> <mo>+</mo> <mn>6</mn> <mo stretchy="false">)</mo> <mo>)</mo> </mrow> </math></EquationSource> <EquationSource Format="TEX">$\ln \Gamma (x+1)/\left (\ln \left (x^{2}+6\right )-\ln (x+6)\right )$</EquationSource> </InlineEquation> on the interval <InlineEquation ID="IEq2"> <EquationSource Format="MATHML"><math> <mi>x</mi> <mo>∈</mo> <mo stretchy="false">(</mo> <mo>−</mo> <mn>1</mn> <mo>,</mo> <mn>1</mn> <mo stretchy="false">)</mo> </math></EquationSource> <EquationSource Format="TEX">$x\in (-1,1)$</EquationSource> </InlineEquation>, supported by well-established functional inequalities where the main idea of the proofs comes from the use of L’Hôpital-style rule for the monotonicity of a ratio of two functions. Our approach can be viewed as a slight modification of the technique presented in Zhao et al. (Publ. Math. (Debr.) 80(3–4):333–342, <CitationRef CitationID="CR17">2012</CitationRef>). We further demonstrate the monotonicity of the function <InlineEquation ID="IEq3"> <EquationSource Format="MATHML"><math> <mo stretchy="false">[</mo> <mn>1</mn> <mo>,</mo> <mo>+</mo> <mi mathvariant="normal">∞</mi> <mo stretchy="false">)</mo> <mo>∋</mo> <mi>s</mi> <mo>↦</mo> <mi>u</mi> <mo stretchy="false">(</mo> <mi>s</mi> <mo stretchy="false">)</mo> <mo stretchy="false">/</mo> <mi mathvariant="normal">Γ</mi> <mo stretchy="false">(</mo> <mi>s</mi> <mo>+</mo> <mi>ρ</mi> <mo stretchy="false">)</mo> <mi mathvariant="normal">Γ</mi> <mo stretchy="false">(</mo> <mi>s</mi> <mo stretchy="false">)</mo> </math></EquationSource> <EquationSource Format="TEX">$[1,+\infty )\ni s\mapsto u(s)/\Gamma (s+\rho )\Gamma (s)$</EquationSource> </InlineEquation> where <i>u</i> is a positive-valued differentiable function on <InlineEquation ID="IEq4"> <EquationSource Format="MATHML"><math> <mo stretchy="false">[</mo> <mn>1</mn> <mo>,</mo> <mo>+</mo> <mi mathvariant="normal">∞</mi> <mo stretchy="false">)</mo> </math></EquationSource> <EquationSource Format="TEX">$[1,+\infty )$</EquationSource> </InlineEquation> and <InlineEquation ID="IEq5"> <EquationSource Format="MATHML"><math> <mi>ρ</mi> <mo>&gt;</mo> <mo>−</mo> <mn>1</mn> </math></EquationSource> <EquationSource Format="TEX">$\rho &gt;-1$</EquationSource> </InlineEquation>, punctuated by a selection of several special cases that highlight its unique characteristics.</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

Monotonic nature of the Gamma function

  • Teodor Bulboacă,
  • Hanaa M. Zayed

摘要

This study begins by examining the monotonic behavior of the function ln Γ ( x + 1 ) / ( ln ( x 2 + 6 ) ln ( x + 6 ) ) $\ln \Gamma (x+1)/\left (\ln \left (x^{2}+6\right )-\ln (x+6)\right )$ on the interval x ( 1 , 1 ) $x\in (-1,1)$ , supported by well-established functional inequalities where the main idea of the proofs comes from the use of L’Hôpital-style rule for the monotonicity of a ratio of two functions. Our approach can be viewed as a slight modification of the technique presented in Zhao et al. (Publ. Math. (Debr.) 80(3–4):333–342, 2012). We further demonstrate the monotonicity of the function [ 1 , + ) s u ( s ) / Γ ( s + ρ ) Γ ( s ) $[1,+\infty )\ni s\mapsto u(s)/\Gamma (s+\rho )\Gamma (s)$ where u is a positive-valued differentiable function on [ 1 , + ) $[1,+\infty )$ and ρ > 1 $\rho >-1$ , punctuated by a selection of several special cases that highlight its unique characteristics.