How to make the following concave function to fit cvx?

max_x log(1+ax/(bx+c)) - q(dx+e), where a, b, c, d, e, q are all non-negative.

Thanks for your kind help!

Hi， yesterday I made it by converting
log(1+ax/(bx+c)) - q(dx+e)
to
log(1+ a/b-(ac/b)*inv_pos(bx+c)) - q(dx+e).
But today it doesn’t work again…
the error is
Disciplined convex programming error:
Cannot perform the operation: {positive constant} .* {positive constant}

This requires a*c/b >= 0.

If that doesn’t resolve it, please show a complete, but minimal reproducible example, with all input data.

And please include all * in your program, i.e., actual code, not math for display with implied * .

I’m sure a*c/b >=0, and it worked the day before yesterday…

Well, if you claim to have done the same thing, and it worked one day, and not the next, and you don’t show us exactly what you did, I don’t think we can provide much help.

If you saw this question, and you were going to reply, what would you tell the poster? Whatever that is, do it.