f(z)- The Complex Variables Program


1/z - Linear fractional transformations

These are selected frames from an animation in which the circles in the left figure (the domain) move to the right. The middle figure in each frame is 1/z applied to the domain. The right figure is also 1/z, but drawn on the Riemann sphere.

On the plane, 1/z can appear extraordinarily complicated - watch what happens to the complement of the image of the disk. It seems to become the interior! On the sphere the action is quite simple.(Question: is there any reason to vary the function to some other linear fractional transformation?)