# Talk:BIBO stability

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## Last section

In the last section, "Frequency domain condition," doesn't it leave out the condition that the number of zeros must be less than the number of poles? This is for both continuous and discrete time that I think this condition was left out.

I think you are right about continuous-time systems - for example, H(s)=s has no poles at all, but is not BIBO stable. In discrete-time, however, there is no such condition, for example H(z)=z is BIBO stable. 94.159.139.235 (talk) 23:59, 24 March 2012 (UTC)

When the page is created, a link to input-to-state stability (ISS) should be added to the See also section. ISS is the nonlinear analog to BIBO stability. —TedPavlic (talk) 18:09, 30 January 2009 (UTC)

## Definition of bounded signal

The definition of a bounded signal in the first section is maybe just confusing? Is it needed to define the input? If so it should be clear that the definition only is valid for the input signal. Since it is not valid for the output signal. Ex. if the output is h(t)=a, it is not integrable, hence it is not BIBO stable. Tibnor (talk) 10:04, 17 December 2010 (UTC)

The definition is valid for the output as well. If the output is y(t)=a, then it is a bounded output. 94.159.139.235 (talk) 00:02, 25 March 2012 (UTC)

## Get confused

In "Frequency-domain condition for linear time invariant systems" section, the formula said

${\displaystyle =\int _{-\infty }^{\infty }{\left|h(t)\right|\left|e^{-j\omega t}\right|dt}}$
${\displaystyle =\int _{-\infty }^{\infty }{\left|h(t)(1\cdot e)^{-j\omega t}\right|dt}}$

According to the triangle inequality, is it need to be the following formula ?

${\displaystyle =\int _{-\infty }^{\infty }{\left|h(t)\right|\left|e^{-j\omega t}\right|dt}}$
${\displaystyle \geq \int _{-\infty }^{\infty }{\left|h(t)(1\cdot e)^{-j\omega t}\right|dt}}$

--Wolfch (talk) 15:46, 1 October 2013 (UTC)

## condition for continuous-time signal

What is written here https://en.wikipedia.org/wiki/BIBO_stability#Continuous-time_signals is completely uncorrect, see https://fr.wikipedia.org/wiki/Stabilit%C3%A9_EBSB#Condition_dans_le_domaine_fr.C3.A9quentiel for a correct derivation. 78.196.93.135 (talk) 14:08, 30 January 2017 (UTC)