To create a proper professional documentation (thesis, book and so on) you need an authoring tool to facilitate the work. Authoring tool is a program that helps you write using hypertext and enable you to create a final application merely by linking together objects, such as a paragraph of text, an illustration, technical data, graphics, expressions and so on at last to produce attractive, professional and useful documentation.

Lyx is an extremely powerful document processor, which allows you to create professional looking documents quickly, easily, with no worries about the style and layout. LyX is a graphical interface WYSIWYM (What You See Is What You Mean) document processor to the LaTeX word processing package that encourages an approach to writing based on the structure of your documents, not their appearance. LaTeX is a typesetting system which is very popular with computer scientists, engineers, mathematicians, physicists etc. Read more
Veusz is a scientific plotting and graphing package written in Python designed to create publication-ready Postscript or PDF output. It uses PyQt4 for display and user-interfaces, and numpy for handling the numeric data. It can create line graphs, XY plots, histograms, shapes, images and contour plots. Graphs are constructed from components, allowing complex layouts to be designed. Read more