Question: Calculating integral

If I calculate the integral:


evalf(Int(z^(1/2)*(diff(z, t)), t = 0 .. 2*Pi))

I get -1.33333333*I

If I calculate

int(z^(1/2)*(diff(z, t)), t = 0 .. 2*Pi)

I get -4/3

so where is the I coming from? Am I doing sth  something   wrong?

I might add: if I calculate the same for z:=0.5+exp(I*t) I get 0 and -I*0.4714....

so what is going different here?

Please Wait...