Why is the error reported {convex} .* {real affine}

1

The goal is the sum of each element in the matrix to the third power, and I put a non-negative constraint on the constraint, and the cubed of an unknown quantity is convex if the unknown quantity is greater than zero, so why is this still an error
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2

Because you didn’t follow CVX’s rules.

Use pow_pos or pow_p, with p = 3.

1 Like
3

Thank you very much. Could you tell me how to write such a goal? I have tried many ways, but they are all wrong
t and c are both constant，u is a variable of 2*1 dimensions
Thank you very much

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4

You need to use square_pos when squaring norm.

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5

Thank you very much for your warm reply，I’ve got a new problem
This error occurs when I run the following code
错误使用 cvx/pow_cvx (line 144)
Disciplined convex programming error:
Illegal operation: pow_p( {convex}, {-1} )

for i=1:I
      for k=2:N
          sum21(k,i)=0;sum22(k,i)=0;
          for n=2:k
              G2=B*log2(1+Pi(n,i)*inv_pos(H^2+2*(u(:,n)-si(:,i))'*u(:,n)));
              sum21(k,i)= sum21(k,i)+tiulo(n,i)*G2;
              L2=t0*fiu(n,i)/ci(i);
              sum22(k,i)=sum22(k,i)+L2;
          end
          sum21(k,i)<=sum22(k,i);
      end
   end

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There’s only one 2 N variable u, and the other parameters are known，G2=Blog2(1+Pi(n,i)inv_pos(H^2+2(u(:,n)-si(:,i))’*u(:,n))); is error
修改翻译结果

6

The argument of inv_pos needs to be concave. But it is not; hence the error.

Have you proven the optimization problem is convex?

7

I refer to a paper, which also uses CVX to solve a problem similar to mine, and proves that G2 is convex for u(n), but I don’t know why I made a mistake in writing the code

8

Please carefully read the link I provided.

9

Can I use rel_entr to solve such problem?

10

Not that i know of. But certainly not unless the problem is convex, whose determination i left in your hands. That said, I have no reason to believe this is a convex problem.

11

Well, thank you for taking the time to answer my childish questions