<p>We define generalized real and imaginary parts of an operator, as well as the generalized <InlineEquation ID="IEq1"> <EquationSource Format="MATHML"><math> <msub> <mi>w</mi> <mrow> <mi>h</mi> <mo>,</mo> <mi>g</mi> </mrow> </msub> <mo stretchy="false">(</mo> <mo>⋅</mo> <mo stretchy="false">)</mo> </math></EquationSource> <EquationSource Format="TEX">$w_{h,g}(\cdot )$</EquationSource> </InlineEquation> numerical radius, which reduces to the <i>t</i>-weighted numerical radius for suitable functions <InlineEquation ID="IEq2"> <EquationSource Format="MATHML"><math> <mi>h</mi> <mo>,</mo> <mi>g</mi> </math></EquationSource> <EquationSource Format="TEX">$h,g$</EquationSource> </InlineEquation>. Usual properties regarding the new numerical radius are shown, as well as various inequalities concerning the ratio between <InlineEquation ID="IEq3"> <EquationSource Format="MATHML"><math> <msub> <mi>w</mi> <mrow> <mi>h</mi> <mo>,</mo> <mi>g</mi> </mrow> </msub> <mo stretchy="false">(</mo> <mo>⋅</mo> <mo stretchy="false">)</mo> </math></EquationSource> <EquationSource Format="TEX">$w_{h,g}(\cdot )$</EquationSource> </InlineEquation> and <InlineEquation ID="IEq4"> <EquationSource Format="MATHML"><math> <mi>w</mi> <mo stretchy="false">(</mo> <mo>⋅</mo> <mo stretchy="false">)</mo> </math></EquationSource> <EquationSource Format="TEX">$w(\cdot )$</EquationSource> </InlineEquation>. In the last section, we give operator matrix inequalities, which generalize the standard numerical radius inequalities, and in one case it is shown that the inequality obtained is sharper than the inequality given by Ammar et al. (Kyungpook Math. J. 65(1):63–75, <CitationRef CitationID="CR6">2025</CitationRef>, Theorem 2.13) for specific operator matrices.</p>

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New generalized numerical radius inequalities for Hilbert space operators

  • Fuad Kittaneh,
  • Vuk Stojiljković

摘要

We define generalized real and imaginary parts of an operator, as well as the generalized w h , g ( ) $w_{h,g}(\cdot )$ numerical radius, which reduces to the t-weighted numerical radius for suitable functions h , g $h,g$ . Usual properties regarding the new numerical radius are shown, as well as various inequalities concerning the ratio between w h , g ( ) $w_{h,g}(\cdot )$ and w ( ) $w(\cdot )$ . In the last section, we give operator matrix inequalities, which generalize the standard numerical radius inequalities, and in one case it is shown that the inequality obtained is sharper than the inequality given by Ammar et al. (Kyungpook Math. J. 65(1):63–75, 2025, Theorem 2.13) for specific operator matrices.