square

Square wave

Syntax

x = square(t)

x = square(t,duty)

Description

x = square(t) generates a square wave with period 2π for the elements of the time array t. square is similar to the sine function but creates a square wave with values of –1 and 1.

x = square(t,duty) generates a square wave with specified duty cycle duty. The duty cycle is the percent of the signal period in which the square wave is positive.

Examples

Generate Square Waves

Create a vector of 100 equally spaced numbers from $$0$$ to $$3\pi$$. Generate a square wave with a period of $$2\pi$$.

t = linspace(0,3*pi)';
x = square(t);

Plot the square wave and overlay a sine. Normalize the x-axis by $$\pi$$. The generated square wave has a value of $$1$$ for intervals [$\mathit{n}\pi ,\left(\mathit{n}+1\right)\pi$) with even $\mathit{n}$ and a value of $$-1$$ for intervals [$\mathit{n}\pi ,\left(\mathit{n}+1\right)\pi$) with odd $\mathit{n}$. The wave never has a value of $$0$$.

plot(t/pi,x,'.-',t/pi,sin(t))
xlabel('t / \pi')
grid on

Repeat the calculation, but now evaluate square(2*t) at 121 equally spaced numbers between $$-\pi$$ and $$2\pi$$. Change the amplitude to $$1.15$$. Plot the wave and overlay a sine with the same parameters. This new wave is negative at $$t=0$$ and positive at the endpoints, $$-\pi$$ and $$2\pi$$.

t = linspace(-pi,2*pi,121);
x = 1.15*square(2*t);

plot(t/pi,x,'.-',t/pi,1.15*sin(2*t))
xlabel('t / \pi')
grid on

Duty Cycle of Square Wave

Generate a 30 Hz square wave sampled at 1 kHz for 70 ms. Specify a duty cycle of 37%. Add white Gaussian noise with a variance of 1/100.

t = 0:1/1e3:0.07;
y = square(2*pi*30*t,37)+randn(size(t))/10;

Compute the duty cycle of the wave. Plot the waveform and annotate the duty cycle.

dutycycle(y,t)

ans = 
0.3639

Input Arguments

t — Time array

vector | matrix | N-D array

Time array, specified as a vector, matrix, or N-D array. square operates along the first array dimension of t with size greater than 1.

Data Types: single | double

duty — Duty cycle

50 (default) | real scalar from 0 to 100

Duty cycle, specified as a real scalar from 0 to 100.

Data Types: single | double

Output Arguments

x — Square wave

vector | matrix | N-D array

Square wave, returned as a vector, matrix, or N-D array.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

GPU Code Generation
Generate CUDA® code for NVIDIA® GPUs using GPU Coder™.

Version History

Introduced before R2006a

R2024a: square supports GPU code generation

The square function supports code generation for graphical processing units (GPUs). You must have MATLAB^® Coder™ and GPU Coder™ to generate CUDA^® code.