Subscripting into an empty matrix is not supported

Question

Tamer 2014-9-22

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https://ww2.mathworks.cn/matlabcentral/answers/155719-subscripting-into-an-empty-matrix-is-not-supported

评论： Tamer 2014-9-27

Hi There,

I have the following simple Matlab code, and I'm trying to implement the HDL code for it. but I got this error "Subscripting into an empty matrix is not supported" for "x(k+2)".

is there anyone could help me on that?

x=amp*sin(2*f*t);

k=1;

km=31416;

UPDN=zeros(1,km,'double');

for k=1:1:km-2;

    if x(k+2)>=x(k);
        UPDN(k)=1;
   else 
        UPDN(k)=0;
   end

end

for k=km-1:1:km;

UPDN(k)=1;

end

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Answer 1

Andrei Bobrov 2014-9-22

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https://ww2.mathworks.cn/matlabcentral/answers/155719-subscripting-into-an-empty-matrix-is-not-supported#answer_152486

在 MATLAB Online 中打开

x = x(:);
UPDN = [x(2:end);[1;1]] >= [x(1:end-2);[0;0]];

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Tamer 2014-9-24

This answer is not working with me, it solved the problem, but I still want the If function and for statement at my program.

Do you have another suggestion please?

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Answer 2

Tamer 2014-9-23

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/155719-subscripting-into-an-empty-matrix-is-not-supported#answer_152613

编辑：Tamer 2014-9-23

在 MATLAB Online 中打开

Thank you Andrei,

your solution fixed my problem but my Matlab program has lots of (for & if statement). Do you have another solution for this problem ? I have to keep the if & For statement as showing at the example below.

for p=2:pp-2

    if (dero(p)+1 == dero(p+1)&& dero(p)+2 == dero(p+2));
       dero2(p+1)=0;
    end

end

Thanks, -- Tamer

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Tamer 2014-9-24

Andrei,

I have to keep the (if)statement and (for) loop at my program, because I have lots of (for) loops and (if) statement at my program. do you have another solution by keeping (if) and (for)?

Thanks for you help -- Tamer

Tamer 2014-9-27