Talk:Hankel matrix

Hankel transform as presented in the text correct?
does the material presented in the section Hankel transform correct? I can make a simple example to violate it! For example, take b1=1, b2=1, b3=2 and you will have detB=1 but detC=-1! —Preceding unsigned comment added by 61.18.170.199 (talk) 09:46, 6 August 2009 (UTC)


 * formula is now correctBPets (talk) 04:34, 1 September 2009 (UTC)


 * Please improve the section on system identification... it currently doesn't begin to suggest how one might actually do this.--Witbrock (talk) 18:15, 2 May 2013 (UTC)

Reference to R. B. Pachori
Bhajan123 (contributions) (talk) has been including references to R. B. Pachori in several articles. Bhajan123 may simply be promoting his or her own work. I recommend removing such references. — Anita5192 (talk) 19:41, 31 July 2016 (UTC)


 * They were removed sometime in the past. Also, user was blocked about a year ago. 67.198.37.16 (talk) 00:00, 15 January 2024 (UTC)

Confusing statement
I can't make any sense of the statement "$$A $$ must satisfy, for all rows $$i$$ and columns $$j$$, $$(A_{i,j})_{i,j \ge 1}$$. ". Is this perhaps a typo? Andylatto (talk) 17:50, 23 June 2021 (UTC)


 * I removed this section. It was garbled, presumably copied from class notes. It was trying to define the Hankel operator, which was already defined in the previous section. 67.198.37.16 (talk) 00:27, 15 January 2024 (UTC)

Remove empty statement
I just removed the following, because it doesn't say anything useful:


 * Given a Hankel operator $$H_\alpha: \ell^2\left(\mathbb{Z}^+ \cup\{0\}\right) \to \ell^2\left(\mathbb{Z}^+ \cup\{0\}\right)$$ over the Hilbert space $$\ell^2(\mathbb Z)$$, the space of square-integrable bilateral complex sequences, and given any $$u \in \ell^2(\mathbb Z)$$, then


 * $$\|u\|_{\ell^2(z)}^2 = \sum_{n=-\infty}^{\infty}\left| u_n \right|^2$$.

The display formula is merely the definition of the norm on that Hilbert space. That norm has nothing to do with the Hankel operator. Thus, it "doesn't say anything useful". Perhaps the intent was ... to say something more? Viewing the article history, this was added by User:Cyphra in May 2020, and there was never anything more than this. 67.198.37.16 (talk) 22:29, 25 January 2024 (UTC)