Rectangular function

Rectangular function or rect function is a fundamental concept in the fields of signal processing, mathematics, and electronic engineering. It is a type of mathematical function that is defined to be 1 over an interval and 0 outside that interval. This function is crucial in the analysis and understanding of signals, particularly in the context of Fourier transforms and waveform shaping.

Definition

The rectangular function, often denoted as \( \text{rect}(t) \), is defined as:

\[ \text{rect}(t) = \begin{cases} 1 & \text{if } |t| < \frac{1}{2} \\ \frac{1}{2} & \text{if } |t| = \frac{1}{2} \\ 0 & \text{if } |t| > \frac{1}{2} \end{cases} \]

This definition implies that the function has a value of 1 within the interval \( -\frac{1}{2} \leq t \leq \frac{1}{2} \) and a value of 0 outside this interval. The points at \( t = \pm\frac{1}{2} \) are often considered as part of the function's transition and can be defined differently depending on the context.

Applications

The rectangular function is widely used in various applications, including:

• Signal Processing: In signal processing, the rect function is used to model idealized signals or to apply window functions in the time domain for Fourier analysis.
• Electronics: In electronic engineering, it is used in the design of pulse modulation schemes and in the analysis of digital signals.
• Mathematics: In mathematics, the rectangular function serves as a simple example of a function that is easy to analyze in the context of Fourier series and Fourier transforms.

Fourier Transform

One of the most important properties of the rectangular function is its Fourier transform. The Fourier transform of \( \text{rect}(t) \) is the sinc function, which is defined as \( \text{sinc}(f) = \frac{\sin(\pi f)}{\pi f} \). This relationship is crucial in understanding the behavior of signals in the frequency domain and is a foundational concept in signal processing and communications.

See Also

• Sinc function
• Fourier transform
• Signal processing
• Pulse modulation

References

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Rectangular function gallery

• Rectangular function
  Rectangular function
• Sinc function (normalized)
  Sinc function (normalized)