# scipy.signal.square#

scipy.signal.square(t, duty=0.5)[source]#

Return a periodic square-wave waveform.

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:
tarray_like

The input time array.

dutyarray_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:
yndarray

Output array containing the square waveform.

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)
```