My professor wrote me this model in matlab script: can you explain this? What does mean by s$\_$gdp$?$ why do we use log $?$ and is Y only about gdp or what? I will sure upvote your answer... if you are really expert give me your linkedin if its possible here to connect and maybe get some tutoring..

$\%$ Define State Space model

Y $=[$s$\_$gdp log$($gdp$)]$;

Z $=[$risk$,$ ca$\_$gdp$]$;

$[$nobs$]=$ size$($Y$,1)$;

Mdl $=$ ssm$($@$($params$)$Function$\_$StateSpace$($params$,$ nobs, d$\_$gdp$,$ Y$,$ Z$))$;