Getting an error message when I use 'triangle()' function.

I wrote a code to create a tiangle wave form for testing my functions as below:

close all; clearvars; clc;
t = 0:0.01:10*pi;
f = 5;
A = 10;
y = A * triangle(2*pi*t);

Unrecognized function or variable 'triangle'.

figure, plot(y);

But I am getting a Command Window error message as below:

Unrecognized function or variable 'triangle'.

Error in ucgenDalga (line 5)

y = A * triangle(2*pi*t);

I tested the code first in MATLAB 2022b and then in MATLAB Online, having the same error message. When I wrote "help triangle" in Command Window, MATLAB responds an answer. But when I use triangle function in my code, I am receiving the above error. I could not have got an answer from Internet search. Any idea is appreciated.

[VBBV]

help triangle 

--- help for Stateflow operator triangle ---

 triangle - Triangle wave test signal
    triangle(x) generates a triangle wave from the input x based on the
    equation,

    Syntax
      triangle(x)

    Input Arguments
      x - Value during test step
        numeric scalar

    See also heaviside, ramp, sawtooth, square

    Introduced in Simulink Test in R2015a
    Documentation for triangle
       doc triangle

[VBBV]

The documentation states this function is for use in Stateflow estimation

[Baris Dogan]

Thank you for your answer.

Answer 1

[Dyuman Joshi]

That help is for a Stateflow operator in SIMULINK (as mentioned in the 1st line), not for a function in MATLAB.

help triangle

--- help for Stateflow operator triangle ---

 triangle - Triangle wave test signal
    triangle(x) generates a triangle wave from the input x based on the
    equation,

    Syntax
      triangle(x)

    Input Arguments
      x - Value during test step
        numeric scalar

    See also heaviside, ramp, sawtooth, square

    Introduced in Simulink Test in R2015a
    Documentation for triangle
       doc triangle

There is no MATLAB function named triangle (atleast not in the available toolboxes, as not all toolboxes are available in the live editor on MATLAB Answers)

which triangle -all

'triangle' not found.

If you want to plot a triangle wave with a given amplitude and period, you can utilize mod -

A = 10;
p = 5;

y = @(x) A*mod(x,p)

y = function_handle with value:
    @(x)A*mod(x,p)

fplot(y)

[Baris Dogan]

Thank you for your answer. I also found sawtooth() in my search but I need a triangular (isosceles triangle) signal not a sawtooth (right triangle) signal. Anyway I assumed there may be a ready made function in MATLAB but it seems I need to write my own code.

[Dyuman Joshi]

In that case, you can use this -

A = 10;
p = 5;

y = @(x) 2*A*abs(mod(x+p/2, p) - p/2)/p;
fplot(y)

[Baris Dogan]

Thank you.

[Dyuman Joshi]

@Baris Dogan, if my answer solved your problem, please consider accepting the answer.

Answer 2

[VBBV]

close all; clearvars; clc;
t = 0:0.01:10*pi;
f = 5;
A = 10;
y = A * sawtooth(2*pi*t);
figure, plot(t,y); xlim([0 2*pi])

[VBBV]

use sawtooth function which can generate triangular waveforms

[Baris Dogan]

Thank you for your answer. I also found sawtooth() in my search but I need a triangular (isosceles triangle) signal not a sawtooth (right triangle) signal. Anyway I assumed there may be a ready made function in MATLAB but it seems I need to write my own code.

[VBBV]

You can modify your code using sawtooth in https://www.mathworks.com/help/signal/ref/sawtooth.html to suit what you want

close all; clearvars; clc;
t = 0:0.01:10*pi;
f = 5;
A = 10;
y = A * sawtooth(2*pi*t,1/2);  % triangle wave with two equal sides 
figure, plot(t,y); xlim([0 pi])