On this set, any in nitely di erentiablefunction is   analytic.
Marden's theorem says that the foci of the Steiner inellipse can be foundby solving an equation over this set. Functions from this set to itself can beholomorphic if they ful ll certain conditions. Argand diagrams are used tovisually represent elements of this set. On this set, any in nitely di erentiablefunction is   analytic. The elements of this algebraically closed set can beexpressed in phasor form. This set is not an ordered  eld because it fails tosatisfy the requirement that every element's square be positive. For ten points, √ −1.
Marden's theorem says that the foci of the Steiner inellipse can be foundby solving an equation over this set.
complex numbers