P. Wu

activity

20122014

most citedHigher-rank Numerical Ranges and Kippenhahn Polynomials

15 citations · 25 across the 6 of their papers we have counts for

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7 papers · 1 filter

math.FA2014★ 1 cited

Upper and Lower Bounds for Numerical Radii of Block Shifts

Hwa-Long Gau, Pei Yuan Wu

For any $n$ -by- $n$ matrix $A$ of the form \[[\begin{array}{cccc} 0 & A_1 & & \\ & 0 & \ddots & \\ & & \ddots & A_{k-1} \\ & & & 0\end{array}],\] we consider two $k$ -by- $k$ matrices…

math.FA2013

Power Partial Isometry Index and Ascent of a Finite Matrix

Hwa-Long Gau, Pei Yuan Wu

We give a complete characterization of nonnegative integers $j$ and $k$ and a positive integer $n$ for which there is an $n$ -by- $n$ matrix with its power partial isometry index equ…

math.FA2013

Structures and Numerical Ranges of Power Partial Isometries

Hwa-Long Gau, Pei Yuan Wu

We derive a matrix model, under unitary similarity, of an $n$ -by- $n$ matrix $A$ such that $A, A^{2}, \dots, A^{k}$ ( $k \geq 1$ ) are all partial isometries, which generalizes the known f…

math.FA2013★ 9 cited

Numerical Radii for Tensor Products of Matrices

Hwa-Long Gau, Kuo-Zhong Wang, Pei Yuan Wu

For $n$ -by- $n$ and $m$ -by- $m$ complex matrices $A$ and $B$ , it is known that the inequality $w (A \otimes B) \leq ∥ A ∥ w (B)$ holds, where $w (\cdot)$ and $∥ \cdot ∥$ denote, respectively…

math.FA2013

Zero-dilation Index of a Finite Matrix

Hwa-Long Gau, Kuo-Zhong Wang, Pei Yuan Wu

For an $n$ -by- $n$ complex matrix $A$ , we define its zero-dilation index $d (A)$ as the largest size of a zero matrix which can be dilated to $A$ . This is the same as the maximum $k$ …

math.FA2013

Numerical Ranges of KMS Matrices

Hwa-Long Gau, Pei Yuan Wu

A KMS matrix is one of the form $$J_n(a)=[{array}{ccccc} 0 & a & a^2 &... & a^{n-1} & 0 & a & \ddots & \vdots & & \ddots & \ddots & a^2 & & & \ddots & a 0 & & & & 0{array}]$$ for $…