Definition:Square Wave

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Definition

A square wave is a periodic real function $S: \R \to \R$ defined as follows:

$\forall x \in \R: \map S x = \begin {cases}

\delta + \gamma & : x \in \openint \alpha {\alpha + \lambda} \\ \delta - \gamma & : x \in \openint {\alpha - \lambda} \alpha \\ \map S {x + 2 \lambda} & : x < \alpha - \lambda \\ \map S {x - 2 \lambda} & : x > \alpha + \lambda \end {cases}$

where:

$\alpha$, $\lambda$, $\gamma$ and $\delta$ are given real constants.


Points of Discontinuity

The points $\alpha + n \lambda$, for $n \in \Z$, are jump discontinuities.

The values $\map S {\alpha + n \lambda}$ may or may not be explicitly defined.


It is a common approach to include either endpoint of the intervals from $\alpha$ to $\alpha + \lambda$, and from $\alpha - \lambda$ to $\alpha$, in order to ensure that the domain of $S$ is simply defined, for example:

$\forall x \in \R: \map S x = \begin {cases}

\delta + \gamma & : x \in \hointr \alpha {\alpha + \lambda} \\ \delta - \gamma & : x \in \hointr {\alpha - \lambda} \alpha \\ \map S {x + 2 \lambda} & : x < \alpha - \lambda \\ \map S {x - \lambda l} & : x \ge \alpha + \lambda \end {cases}$

Another approach is to make $\map S {\alpha + n \lambda} = \delta$ for all $n \in \Z$.


The precise treatment of the discontinuities is often irrelevant or immaterial.


Graph of Square Wave

The graph of $S$ is given below:

Square-wave-general.png


Also see

  • Results about square waves can be found here.