The part of the complex plane of positive imaginary part is often called the *upper half plane*, sometimes denoted $\mathfrak{H}$.

Accodingly the *lower half plane* is the subset of complex numbers with negative imaginary part.

- Wikipedia,
*Upper half plane*

Last revised on September 6, 2017 at 15:19:57. See the history of this page for a list of all contributions to it.