Creating a piecewise function

Question

Ali Kiral 2021-6-14

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/856105-creating-a-piecewise-function

评论： Ali Kiral 2021-6-14

I am trying to make that triangular wave for one period with the code (I don't want to plot it, just to generate x and y values in the interval)

x = 0 : 0.5 : 4;
for k = 1 : length(x)
  if x(k) < 1
    y(k) = 0;
elseif x(k) >= 1 & x(k) < 2
    y(k) = x-1;
elseif x(k) >=2 & x(k) < 3
    y(k) = 3-x;
   elseif x(k)>=3
    y(k) = 0;
  end
end

Then Matlab returns 'In an assignment A(I) = B,...' I think I am not trying to assign a scalar to a vector or vice versa, what is the problem here?

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Answer 1

Voss 2021-6-14

2
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在 MATLAB Online 中打开

The line:

y(k) = x-1;

tries to assign the entire vector x-1 to a single element (the kth element) of y. Instead it should be:

y(k) = x(k)-1;

Similarly the line:

y(k) = 3-x;

should be:

y(k) = 3-x(k);

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Ali Kiral 2021-6-14

Got it, thanks

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Answer 2

Scott MacKenzie 2021-6-14

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/856105-creating-a-piecewise-function#answer_724710

在 MATLAB Online 中打开

A few bugs in your code. Here's the fix (although there are easier ways to do this):

x = 0 : 0.5 : 4;
for k = 1 : length(x)
    if x(k) < 1
        y(k) = 0;
    elseif x(k) < 2
        y(k) = x(k)-1;
        
    elseif x(k)  < 3
        y(k) = 3-x(k);
        
    else
        y(k) = 0;
    end
end
plot(y);