how to sum unit function and step function

Question

chae hyeon shin 2020-5-1

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/522176-how-to-sum-unit-function-and-step-function

回答： VIVEK 2022-9-20

在 MATLAB Online 中打开

I want to calculate the convolution of x(t) and h(t).

Here is my code :

clear;
t = [ -10 : 0.01 : 10 ];
 
xt = ( t >= -2 ) & ( t <= 2) + (t == 1)
ht = ( t >= -1 ) & ( t <= 2) + 2*(t == 0) + (t == 3)
plot(t,ht);
ylim([-0.5 2]);
 
yt = conv(xt,ht,'same');
t1 = [-inf, inf];
plot(t1,yt);

I'm not sure that xt and ht are correct.

Moreover, there is an error with last line.

HELP ME

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Ameer Hamza 2020-5-1

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Answer 1

Ajay Pattassery 2020-5-4

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/522176-how-to-sum-unit-function-and-step-function#answer_430119

在 MATLAB Online 中打开

ml_ans_final.png

I assume you are trying to do the convolution of xt, ht as attached in the image.

t = ( -10 : 0.01 : 10 );
 
xt = (( t >= -2 ) & ( t <= 2)) + (t == 1);
ht = (( t >= -1 ) & ( t <= 2)) + 2*(t == 0) + (t == 3);
subplot(3,1,1);plot(t,xt);
ylabel('xt');
subplot(3,1,2);plot(t,ht) 
ylabel('ht');
yt = .01*conv(xt,ht,'same');
subplot(3,1,3);plot(t,yt);
ylabel('yt');

I have just edited your above code.

If you are doing convolution of continuous signals by approximating as above in MATLAB, you need to multiply the output of conv with dt. In your case .01. What you are basically doing is approximating the continuous signal with boxes of width .01 and doing the discrete convolution. Hence while doing convolution, the integration can be achieved by mulitplying with dt.