What is the error mean?

What is the error mean?

The following error occurred when converting from CVX to double
Cannot convert from CVX to double

You probably need to declare temp as an expression holder (array). http://cvxr.com/cvx/doc/basics.html#assignment-and-expression-holders .

Thank you,Mark ! I have solved it.

I have another question.
when I use log_sum_inv() in CVX, why CVX occur the error: Function or variable log_sum_inv() is not defined ? But when I replace log_sum_inv() by log_sum_exp(),there is no error.

Because CVX does not provide log_sum_inv. It would be possible to add such a function to CVX (write your own?) using the formulations in 5.2.7 of https://docs.mosek.com/modeling-cookbook/expo.html , but it has not been.

OK, Thank you for your reply!
I will try to transform log_sum_exp() tomorrow by refering http://ask.cvxr.com/t/using-cvxquad-pade-approximant/1031 .

I am not sure what you are planning, because you link to an already deleted SPAM post. But in the first log_sum_inv formulation approach in the link from my preceding post, log_sum_exp would be used to implement the first constraint in that formulation in CVX.