Plotting a function with different conditions

Question

wiig krist 2014-4-2

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/124204-plotting-a-function-with-different-conditions

评论： wiig krist 2014-4-2

am trying to build and plot a Triangular function with an amplitude of 1 , starting in second 1, reaching the max in second 3 and going back to zero in second 4,

x(A,t1,t2,t3,t) =

A/t2-t1 *(t-t1), t1<=t<=t2
A/t2-t3 *(t-t3),t2<=t< t3
0, elsewhere

the problem is that I can't find a way to add the two conditions to the function ,even with one condition I get only a straight line

here is what I got so far, please give me an idea to how to add them both

the script :

    fs = 20; %freq
      t = 0:1/fs:5;
    t1=1; t2=3;  t3=4;
    A=1; %amplitude
    x2 = mytri(A,t1,t2,t3,t);
     plot (t,x2,'.-')
     axis([ -2 5 -2 5])

the function

function x2 = mytri(A,t1,t2,t3,t)
 x2=A/t2-t1*t-t1*(t1<=t<=t2);

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Answer 1

Joseph Cheng 2014-4-2

1
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/124204-plotting-a-function-with-different-conditions#answer_131806

Look at each portion of your mytri() function. (side note your x2 equation doesn't match the first condition for x (you're missing a t1^2. as t1*(t-t1)=t1*t-t1^2))

you can use the find() function to find when t1<=t and t<=t2. or use the x(t1<=t and t<=t2) to satisfy your conditions.