There is my part of function codes.

d= norm(X, 2);

Where X= A*x-b is a convex function’s input parameter:
A is 4*4 matrix

n= 4

b is 4*1 matrix

variable x(n) ;

minimize( sum(myFunction(A*x-b)) );

Then cvx compiler return:

Error using cvx/norm (line 52)

Disciplined convex programming error:

Cannot perform the operation norm( {convex}, 1 )

Error in myFunction(line 3)

d= norm(X, 2);

It’s perplexing me long time.

Thanks for your response.