Function isreal - complex numbers:
The function isreal returns 1 for logical true when there is no imaginary part of the argument, or 0 for false when the argument does have an imaginary part (even if it is 0). For illustration,
>> isreal(z1)
ans =
0
>> z5 = complex(3)
z5 =
3
>> isreal(z5)
ans =
0
>> isreal(3.3)
ans =
1
For the variable z5, however it displays the answer as 3, it is really stored as 3 + 0i, and that is how it is exhibited in the Workspace Window. And hence, isreal returns logical false as it is stored as a complex number.