{convex} + {concave}

In the expression E_cp2, f0 is a vector variable, and the rest are vector constants。Why is this error reported?Does anyone know. thank you very much。

Apparently, there is at least one term in the sum for which beta.*Dk.*Ck*theta0_k is negative, which would make that term concave. And at least one term for which that is positive, making that term convex.

thank you very much. I didn’t notice that there could be negative numbers in Dk or Ck. If I guarantee that Dk, Ck are non-negative, I can guarantee that E_cp2 is convex. I understand this right?

Presuming that beta and theta0_k also are nonnegative, then yes.

All that really matters is the sign of the product of all the items which multiply square(f0) .

thank you very much. Your reply is very useful to me.