{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。

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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.