This manual page describes the GNU version of eqn, which is part of the groff document formatting system. eqn compiles descriptions of equations embedded within troff input files into commands that are understood by troff. Normally, it should be invoked using the -e option of groff. The syntax is quite compatible with UNIX eqn. The output of GNU eqn cannot be processed with UNIX troff; it must be processed with GNU troff. If no files are given on the command line, the standard input will be read. A filename of - will cause the standard input to be read.
eqn searches for the file eqnrc using the path .:/usr/ lib/groff/tmac :/usr/ lib/tmac. If it exists, eqn will process it before the other input files. The -R option prevents this.
GNU eqn does not provide the functionality of neqn: it does not support low-resolution, typewriter-like devices (although it may work adequately for very simple input).
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