فهرس المقالات numerical radius

• حرية الوصول المقاله
  • صفحة الملخص
  • نص كامل
  
  1 - توسیع شعاع عددی برای عملگرها در فضای هیلبرت 〖-C〗^*مدول
  محسن شاه حسینی بهارک موسوی
  در این مقاله ابتدا تعریف جدیدی از شعاع عددی برای عملگرهای دارای الحاق بر روی یک فضای هیلبرت مدول ارایه و سپس روابطی بین نرم عملگری با این شعاع عددی جدید معرفی می­شود. این نامساوی‌ها به عنوان توسیعی از نامساوی‌های مشهور ثابت شده توسط سایر ریاضیدانان برای عملگرهای خطی أکثر

  در این مقاله ابتدا تعریف جدیدی از شعاع عددی برای عملگرهای دارای الحاق بر روی یک فضای هیلبرت مدول ارایه و سپس روابطی بین نرم عملگری با این شعاع عددی جدید معرفی می­شود. این نامساوی‌ها به عنوان توسیعی از نامساوی‌های مشهور ثابت شده توسط سایر ریاضیدانان برای عملگرهای خطی و کران‌دار تعریف شده بر روی فضای هیلبرت می‌باشد. تفاصيل المقالة
• حرية الوصول المقاله
  • صفحة الملخص
  • نص كامل
  
  2 - Some results on higher numerical ranges and radii of quaternion matrices
  Gh. Aghamollaei N. Haj Aboutalebi
  ‎Let $n$ and $k$ be two positive integers‎, ‎$k\leq n$ and $A$ be an $n$-square quaternion matrix‎. ‎In this paper‎, ‎some results on the $k-$numerical range of $A$ are investigated‎. ‎Moreover‎, ‎the notions of $k$-numerical أکثر

  ‎Let $n$ and $k$ be two positive integers‎, ‎$k\leq n$ and $A$ be an $n$-square quaternion matrix‎. ‎In this paper‎, ‎some results on the $k-$numerical range of $A$ are investigated‎. ‎Moreover‎, ‎the notions of $k$-numerical radius‎, ‎right $k$-spectral radius and $k$-norm of $A$ are introduced‎, ‎and some of their algebraic properties are studied‎. تفاصيل المقالة
• حرية الوصول المقاله
  • صفحة الملخص
  • نص كامل
  
  3 - Some improvements of numerical radius inequalities via Specht’s ratio
  Y. Khatib M. Hassani
  We obtain some inequalities related to the powers of numericalradius inequalities of Hilbert space operators. Some results thatemploy the Hermite-Hadamard inequality for vectors in normed linearspaces are also obtained. We improve and generalize someinequalities with re أکثر

  We obtain some inequalities related to the powers of numericalradius inequalities of Hilbert space operators. Some results thatemploy the Hermite-Hadamard inequality for vectors in normed linearspaces are also obtained. We improve and generalize someinequalities with respect to Specht's ratio. Among them, we showthat, if $A, B\in \mathcal{B(\mathcal{H})}$ satisfy in someconditions, it follows that \begin{equation*} \omega^2(A^*B)\leq \frac{1}{2S(\sqrt{h})}\Big\||A|^{4}+|B|^{4}\Big\|-\displaystyle{\inf_{\|x\|=1}} \frac{1}{4S(\sqrt{h})}\big(\big\langle \big(A^*A-B^*B\big) x,x\big\rangle\big)^2 \end{equation*} for some $h>0$, where $\|\cdot\|,\,\,\,\omega(\cdot)$ and $S(\cdot)$denote the usual operator norm, numerical radius and the Specht'sratio, respectively. تفاصيل المقالة
• حرية الوصول المقاله
  • صفحة الملخص
  • نص كامل
  
  4 - New lower bound for numerical radius for off-diagonal $2\times 2$ matrices
  B. Moosavi M. Shah Hosseini
  10.30495/jlta.2024.2002723.1602
  New norm and numerical radius inequalities for operators on Hilbert space are given. Among other inequalities, we prove that if $ A, B \in B(H) $, then \[\Vert A \Vert - \frac{3 \Vert A-B^* \Vert }{2} \leq \omega\left(\left[\begin{array}{cc} 0 & A \\ B & 0 \end{array}\r أکثر

  New norm and numerical radius inequalities for operators on Hilbert space are given. Among other inequalities, we prove that if $ A, B \in B(H) $, then \[\Vert A \Vert - \frac{3 \Vert A-B^* \Vert }{2} \leq \omega\left(\left[\begin{array}{cc} 0 & A \\ B & 0 \end{array}\right]\right).\] Moreover, $\omega(AB) \leq \frac{3}{2} \Vert Im(A) \Vert \Vert B \Vert + D_{B}\; \omega(A) $. In particular, if $ A $ is self-adjointable, then $\omega(AB) \leq D_{B} \Vert A \Vert$, where $D_{B}=\underset{\lambda \in \mathbb{C}}{\mathop{\inf}}\,\left\| B-\lambda I \right\|$. تفاصيل المقالة
• حرية الوصول المقاله
  • صفحة الملخص
  • نص كامل
  
  5 - Advanced Refinements of Numerical Radius Inequalities
  Farzaneh Pouladi Najafabadi Hamid Moradi
  10.30495/ijm2c.2021.684828
  By taking into account that the computation of the numerical radius is an optimization problem, we prove, in this paper, several refinements of the numerical radius inequalities for Hilbert space operators. It is shown, among other inequalities, that if A is a bounded l أکثر

  By taking into account that the computation of the numerical radius is an optimization problem, we prove, in this paper, several refinements of the numerical radius inequalities for Hilbert space operators. It is shown, among other inequalities, that if A is a bounded linear operator on a complex Hilbert space, thenω(A)≤½√(|| |A|2+|A*|2||+|| |A| |A*|+|A*| |A| ||),where ω(A), ||A||, and |A| are the numerical radius, the usual operator norm, and the absolute value of A, respectively. This inequality provides a refinement of an earlier numerical radius inequality due to Kittaneh, namely,ω(A)≤½(||A||+||A2||)½.Some related inequalities are also discussed. تفاصيل المقالة
• حرية الوصول المقاله
  • صفحة الملخص
  • نص كامل
  
  6 - Norm and Numerical Radius Inequalities for Hilbert Space Operators
  Mohsen Omidvar Mahdi Ghasvareh
  10.30495/ijm2c.2022.1932741.1214
  In this paper, we present several numerical radius and norm inequalities for sum of Hilbert space operators. These inequalities improve some earlier related inequalities. For $A,B\in B\left( H \right)$, we prove that\[\omega \left( {{B}^{*}}A \right)\le \sqrt{\frac{1}{2 أکثر

  In this paper, we present several numerical radius and norm inequalities for sum of Hilbert space operators. These inequalities improve some earlier related inequalities. For $A,B\in B\left( H \right)$, we prove that\[\omega \left( {{B}^{*}}A \right)\le \sqrt{\frac{1}{2}{{\left\| A \right\|}^{2}}{{\left\| B \right\|}^{2}}+\frac{1}{2}\omega \left( {{\left| B \right|}^{2}}{{\left| A \right|}^{2}} \right)}\le 4\omega \left( A \right)\omega \left( B \right).\] تفاصيل المقالة