Error in function at if-elseif

Question

Raul Vaida 2018-3-10

0
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评论： Raul Vaida 2018-3-10

I've got the error Output argument "val" (and maybe others) not assigned during call to "yt". yt(x) funtion:

function [val] = yt(x)
if ((-9<=x) & (x<-3)) | ((3<=x) & (x<=9))
    val = sin(5*x);
elseif (-3<=x) & (x<3)
    val = cos(x) - cos(3) - sin(15);
end

and i call the function using the following

   x = -9:9;
  val = yt(x)

I've got no output from this.

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per isakson 2018-3-10

编辑：per isakson 2018-3-10

Read the documentation on if-else-end
See Debug a MATLAB Program
It's good practice to have an else-clause

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Answer 1

Ahmet Cecen 2018-3-10

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https://ww2.mathworks.cn/matlabcentral/answers/387547-error-in-function-at-if-elseif#answer_309442

编辑：Ahmet Cecen 2018-3-10

在 MATLAB Online 中打开

x is a vector at this point so your comparisons are not resolving to a single true false. I am guessing this is what you meant to do:

 x = -9:9;
 val = yt(x)
 function [val] = yt(x)
    for i = 1:length(x)
        if ((-9<=x(i)) && (x(i)<-3)) || ((3<=x(i)) && (x(i)<=9))
            val(i) = sin(5*x(i));
        elseif (-3<=x(i)) && (x(i)<3)
            val(i) = cos(x(i)) - cos(3) - sin(15);
        end
    end
 end