Thanks in advance for your help and support. I know that this is common topic, posted by many before me. I have read their problems. However, I proved, and it is known, that the following is convex in r .t=(1+0.5*r*λ*v)/(r-λ) [this is a queuing delay equation]
I’ve expressed it in CVX as t>=(1+0.5*r*λ*v)*inv_pos(r-λ). However, an error appears as shown in the title. Please, is there a way to express it to avoid this error (real affine*convex)?
Well, now that you say t is a variable, what counts is joint convexity in r and t, not in r alone.
You haven’t shown us the full context or problem. Perhaps linear fractional or quasiconvex optimization techniques presented in Convex Optimization – Boyd and Vandenberghe can help you use CVX, depending on what your problem actually is. Or perhaps you’re headed for the dreaded nonconvex categorization.
.I don’t think there’s much point to including the t <= tmax constraint, so just leave it out… If the optimal t <= tmax, declare victory, otherwise, call it infeasible, or whatever you feel like doing.