Integration in time knowing the initial condition, from simulink to matlab

Hi all,

I'm trying to rewrite a simulink model in only matlab code (script). How can I rewrite the simulink block 1/s on matlab script, in order to give me the same results?

I mean: on simulink, I have the 1D "x_dot" line that enter in "1/s" block, giving out "x" line. How can I write the same on matlab script, knowing the initial condition?

thanks!