How do I set an initial value for an input in a MATLAB Function Block in Simulink?

This is the function description.

function Y = fcn(U)

Y=U*2;

I want to set intial value for U at the start of simulation. I am unable to set initial value in the function block data editor.

Below is the simulink model:

Answer 1

[Fangjun Jiang]

The initial value of "U" is determined by the 1/z block. Set the initial value there.