Introduction

ePiX, a collection of batch-oriented utilities for *nix, creates mathematically accurate line figures, plots, and movies using easy-to-learn syntax. L^ATEX and dvips comprise the typographical rendering engine, while ImageMagick is used to create bitmapped images and animations. The user interface resembles that of L^ATEX itself: You prepare a short scene description in a text editor, then ``compile'' the input file into a picture. Default output formats are eepic (a plain text enhancement to the L^ATEX picture environment), eps, pdf, png, and mng.

ePiX's strengths include:

• Quality of output: ePiX creates mathematically accurate, publication-quality figures whose appearance matches that of L^ATEX. Typography may be put in a figure as easily as in an ordinary L^ATEX document.

• Ease of use: Figure objects and their attributes are specified by simple, descriptive commands.

• Flexibility: In ePiX, an object is described by its attributes and Cartesian location; as in L^ATEX, printed appearance is determined when the figure is compiled. A well-designed figure can be altered dramatically, yet precisely, with minor changes to the input file.

• Power and extendability: ePiX inherits the power of C++ as a programming language; variables, data structures, loops, and recursion can be used to draw complicated plots and figures with just a few lines of input. External code can be incorporated in an ePiX figure with a command line option or by using a Makefile.

• Economy of storage and transmission: For a document containing many figures, a compressed tar file of the L^ATEX sources and ePiX files is typically a few percent the size of the compressed PostScript file.

• License: ePiX is Free Software. You are granted the right to use the program for whatever purpose, and to inspect, modify, and re-distribute the source code, so long as you do not restrict the rights of others to do the same. In short, the license is similar to the terms under which theorems are published.

The relationship of ePiX to a graphical drawing program is analogous to the relationship between L^ATEX and a word processor; ePiX facilitates logical structuring of mathematical figures. Though ePiX makes a few stylistic defaults to streamline the creation of simple figures, it imposes no internal restrictions on the contents or appearance of a figure; aesthetic and practical decisions are left to the user.

This manual is meant to be read in stages rather than ``cover to cover''. If you are a:

• Potential user, you may wish to skip immediately to ``Software Dependencies'' before investing additional time.

• New user, please proceed from here until you have enough understanding to play with the software, then experiment with the samples files while reading Chapter 2, or return to the manual as needed.

• More advanced user, browse at will, probably starting with Chapter 3.

In any case, please don't hesitate to contact the author or join the mailing list if you have questions or comments (good or bad) about the software or manual, or if you are willing and able to join in developmment.

Under the philosophy that people learn most easily when ideas are introduced in context, this manual is relatively conversational, and occasionally redundant (especially between portions meant for readers at different levels of familiarity). Throughout, you are assumed to be familiar with L^ATEX and basic linear algebra (the description of points, vectors, lines, and planes in three-dimensional space). Other material, such as C++ syntax, is introduced as needed.