def unit_tangent ( self , t ) : dseg = self . derivative ( t ) return dseg / abs ( dseg )
does python have an inverse tangent function
returns the unit tangent vector of the segment at t ( centered at the origin and expressed as a complex number ) .
def unit_tangent(self, t):
        """returns the unit tangent vector of the segment at t (centered at
        the origin and expressed as a complex number)."""
        dseg = self.derivative(t)
        return dseg/abs(dseg)