How can I plot multiple signals with unit step signal

Question

Aous Younis 2013-11-15

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https://ww2.mathworks.cn/matlabcentral/answers/106260-how-can-i-plot-multiple-signals-with-unit-step-signal

评论： Aous Younis 2013-11-15

采纳的回答： Azzi Abdelmalek

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I need to plot this function:

v(t)=(2t+1)[u(t)-u(t-1)]+3[u(t-1)-u(t-2)]+(-t+3)[u(t-2)-u(t-3)]

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Answer 1

Azzi Abdelmalek 2013-11-15

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t=-5:0.1:5
v=(2*t+1).*(heaviside(t)-heaviside(t-1))+3*(heaviside(t-1)-heaviside(t-2))+(-t+3).*(heaviside(t-2)-heaviside(t-3))
plot(t,v,'linewidth',4)

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Aous Younis 2013-11-15

Thanks a lot

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Answer 2

Wayne King 2013-11-15

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https://ww2.mathworks.cn/matlabcentral/answers/106260-how-can-i-plot-multiple-signals-with-unit-step-signal#answer_115318

编辑：Wayne King 2013-11-15

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Looks to me like this just simplifies to:

\delta(t) +3\delta(t-1) + \delta(t-2)

N = 128;
 sig = zeros(N,1);
 idx = 1:3;
 sig(idx) = [1 3 1];
 stem(sig)

u(t)-u(t-1) is like the derivative of the unit step at t, which is the delta function (distribution)

You can see it's equal if you implement your equation above using the differences of the translated unit step functions:

   stepfunc = ones(128,4);
  stepfunc(1,2) = 0;
  stepfunc(1:2,3) = 0;
  stepfunc(1:3,4) = 0;
t = (0:127)';
v1 = 2*t+1;
v2 = -t+3;
v = v1.*(stepfunc(:,1)-stepfunc(:,2))+ 3*(stepfunc(:,2)-stepfunc(:,3))+...
v2.*(stepfunc(:,3)-stepfunc(:,4));
subplot(211)
stem(v)
subplot(212)
stem(sig)