nested if or piecewise function

can someone explain to me how to do matlab coding for this piecewise function. did i have to do nested if coding to solve this function

[tilman knebel]

The fastest way is, to evaluate it for all required t at once: create the target array with "zeros" and fill in the solution for each of both partitions.

[Mohammad Sami]

You can use a switch statement

switch true
    case t <= t_prime
        out = 0
    case t <= Y && t > t_prime
        out = 3 % rest of your expression; 
    otherwise
        out = 1 % rest of your expression;
end