`scipy.signal._waveforms:square`

source: /scipy/signal/_waveforms.py :84

Signature

def square ( t , duty = 0.5 )

Summary

Return a periodic square-wave waveform.

Extended Summary

The square wave has a period 2*pi, has value +1 from 0 to 2*pi*duty and -1 from 2*pi*duty to 2*pi. duty must be in the interval [0,1].

Note that this is not band-limited. It produces an infinite number of harmonics, which are aliased back and forth across the frequency spectrum.

Parameters

t : array_like: The input time array.
duty : array_like, optional: Duty cycle. Default is 0.5 (50% duty cycle). If an array, causes wave shape to change over time, and must be the same length as t.

Returns

y : ndarray: Output array containing the square waveform.

Notes

Array API Standard Support

square has experimental support for Python Array API Standard compatible backends in addition to NumPy. Please consider testing these features by setting an environment variable SCIPY_ARRAY_API=1 and providing CuPy, PyTorch, JAX, or Dask arrays as array arguments. The following combinations of backend and device (or other capability) are supported.

====================  ====================  ====================
Library               CPU                   GPU
====================  ====================  ====================
NumPy                 ✅                     n/a                 
CuPy                  n/a                   ⛔                   
PyTorch               ⛔                     ⛔                   
JAX                   ⛔                     ⛔                   
Dask                  ⛔                     n/a                 
====================  ====================  ====================

See dev-arrayapi for more information.

Examples

A 5 Hz waveform sampled at 500 Hz for 1 second:

import numpy as np
from scipy import signal
import matplotlib.pyplot as plt
t = np.linspace(0, 1, 500, endpoint=False)

✓

plt.plot(t, signal.square(2 * np.pi * 5 * t))
plt.ylim(-2, 2)

✗

A pulse-width modulated sine wave:

plt.figure()

✗

sig = np.sin(2 * np.pi * t)
pwm = signal.square(2 * np.pi * 30 * t, duty=(sig + 1)/2)

✓

plt.subplot(2, 1, 1)
plt.plot(t, sig)
plt.subplot(2, 1, 2)
plt.plot(t, pwm)
plt.ylim(-1.5, 1.5)

✗

Aliases

scipy.signal.square