One way to write this is to create an anonymous function
f = @(t) 0.2*exp(-1i*(8*pi*t-pi/2))+0.585*exp(-1i*(7*pi*t-deg2rad(78.69)));
and then run it like this
>> f(0)
ans =
0.1147 + 0.7736i
>> f(1)
ans =
-0.1147 - 0.3736i
>> f(2)
ans =
0.1147 + 0.7736i
>> f(pi)
ans =
0.0177 + 0.3937i
Read here about anonymous function: https://www.mathworks.com/help/matlab/matlab_prog/anonymous-functions.html
Alternatively, create a function file named myFun.m (or whatever you want. The name of file and function must be same) and define a function like this
function y = myFun(t)
y = 0.2*exp(-1i*(8*pi*t-pi/2))+0.585*exp(-1i*(7*pi*t-deg2rad(78.69)));
end
and then you can call it like this myFun(0), myFun(pi), etc.
