can the derivative of a closed complex contour at any point be zero?

49 Views Asked by At

If C is a closed contour in the complex plane parametrized by z(t)=u(t)+i*v(t), can there be any point where z'(t)=0?

1

There are 1 best solutions below

0
On BEST ANSWER

Yes, as was shown by Daniel Fischer: $$z(t) = e^{it^3}; \quad t\in [-\sqrt[3]{\pi},\sqrt[3]{\pi}]$$

(Or take any closed contour and compose its parametrization with $(t-a)^3$.)