Hello everybody!

I’m using CVX tool(installed on Matlab) to optimal y = log2(A*x-b) with A,b is 2 matrix.

My code follow:

```
A = [1 2 3 4; 5 6 7 8; 9 10 11 12; 13 14 15 16];
b = [1;2;3;4];
cvx_begin
variable x(4)
expression y
y = log2(A*x-b)
minimize (norm(y))
t = x
cvx_end
```

But, It has error: “Undefined function ‘log2’ for input arguments of type ‘cvx’.”. I don’t know how to use function ‘log2’ in CVX tool.

Please help me, thanks you !