square - Square wave - MATLAB (original) (raw)

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Syntax

Description

[x](#d126e271132) = square([t](#d126e271063)) generates a square wave with period 2_π_ 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.

example

[x](#d126e271132) = square([t](#d126e271063),[duty](#d126e271101)) 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.

example

Examples

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

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

Plot the square wave and overlay a sine. Normalize the _x_-axis by π. The generated square wave has a value of 1 for intervals [nπ,(n+1)π) with even n and a value of -1 for intervals [nπ,(n+1)π) with odd 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 -π and 2π. 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, -π and 2π.

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

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

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(2pi30*t,37)+randn(size(t))/10;

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

Input Arguments

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

Data Types: single | double

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

Data Types: single | double

Output Arguments

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

Extended Capabilities

Version History

Introduced before R2006a

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