How to generate a sawtooth wave

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Tze Chwen Lim
Tze Chwen Lim 2017-12-25
回答： Sohan Das 2021-11-18
I get the graph i want.But the amplitude is from -10 to 10. Can i know how can i change it to 0 to 10 and keep the same graph?
Here is what i tried so far: T=2*4; Fs=1000; dt = 1/Fs; t = 0:dt:T-dt; x =-10*sawtooth(2*pi*t);
plot(t,x) grid on

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采纳的回答

Star Strider
Star Strider 2017-12-25
编辑：Star Strider 2017-12-25
You only need to make 2 changes:
T=2*4;
Fs=1000;
dt = 1/Fs;
t = 0:dt:T-dt;
x = sawtooth(2*pi*t); % <— REMOVE THE ‘-10’ HERE
x = (x + 1)*5; % <— ADD THIS LINE
plot(t,x)
grid on
  2 个评论
Tze Chwen Lim
Tze Chwen Lim 2017-12-26
编辑：Tze Chwen Lim 2017-12-26
Thank you but can i know why i need to add that (x+1)*5? And the time need to be in ms so when i multiplies the time with 10^-3 , the graph goes wrong why would this happen?
Star Strider
Star Strider 2017-12-26
My pleasure.
The default output amplitude of the sawtooth function is ±1, so adding 1 produces an amplitude of 0 to +2. Multiplying that by 5 produces the 0 to +10 amplitude you want.
Your time already appears to be in milliseconds because of the way you defined ‘dt’. You do not need to multiply it by anything.
You can label the x-axis as:
xlabel('Time (ms)')
or if you want to label it in seconds, this works:
plot(t,x)
grid on
xt = get(gca, 'XTick');
set(gca, 'XTick',xt, 'XTickLabel',xt*1E-3)
xlabel('Time (seconds)')
Here, you simply re-label the tick labels. Everything else remains the same.

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更多回答（3 个）

Boris Adum
Boris Adum 2021-6-12
You can also write a function that would generate that wave. If you name your amplitude A, and the width of one tooth W then you can write two functions.
  • If you want the function to go from 0 to A
%define amplitude
A = 10; %set your own value
%define width of one tooth
W=5; %set your own value
syms x y;
y=A/W*(x-(W*fix(x/W)))
%plot the function over an interval
fplot(y,[0,3*W]) %set your own limits for ploting
  • If you want the function to go from -A to A
clear %clear old variables if needed
A=10; %amplitude limits of the sawtooth wave -A to A
W=5; %witdh/step of the sawtooth wave
syms x y;
y=((2*A)/W)*(x-(fix(x/W)*W))-A
fplot(y,[0,5*W]) %Plots five teeth
Sohan Das
Sohan Das 2021-11-18
T=2*4;
Fs=1000;
dt = 1/Fs;
t = 0:dt:T-dt;
x = sawtooth(2*pi*t); % <— REMOVE THE ‘-10’ HERE
x = (x + 1)*5; % <— ADD THIS LINE
plot(t,x)
grid on
Sohan Das
Sohan Das 2021-11-18
T=2*4;
Fs=1000;
dt = 1/Fs;
t = 0:dt:T-dt;
x = sawtooth(2*pi*t);
x = (x + 1)*5;
plot(t,x)
grid on

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