How to convert double values to cvx values

Code information:
variable u(N*K) complex
maximize( fun1_Rku_Kt_sum(K, Kt, Ak_save, Bk_save, u) )
subject to
C * x == d
norm( x, Inf ) <= e

Error information:
Unable to perform assignment because value of type ‘cvx’ is not
convertible to ‘double’.

Apparently, this is due to something going on in fun1_Rku_Kt_sum, which you haven;t shown us.

Without seeing your code, my guess is that you need to use an expression holder, i.e., declare a vector or matrix or array expression, as described at .The error arises when you attempt to assign something to part of a vector or matrix or array expression, without first defining it as an expression of the appropriate dimensions.

Thanks for your suggestions!