Description:

GNU TeXmacs is a free what-you-see-is-what-you-get mathematical text
editor, which was both inspired by TeX and GNU Emacs. The program
implements high quality typesetting using TeX fonts, but it is also
provides a user friendly interface.

The high typesetting quality still goes through for automatically
generated formulas, and it is possible to use TeXmacs as an interface
to computer algebra systems. GNU TeXmacs also supports the
Guile/Scheme extension language, which makes it possible to adapt the
user interface to specific needs and even to extend the editor.