EQN(1)

💖 bestie, meet eqn(1), neqn, and checkeq 💖

okay so gather round, because this is the Unix math-glam trio and they are literally here to typeset mathematics. No cap, the energy is immaculate. 💅✨

🌸 NAME 🌸

eqn, neqn, checkeq — typeset mathematics. That's the name, that's the assignment, that's the whole main-character job. 🎀

💫 SYNOPSIS 💫

eqn [-dxy] [-fn] [-sn] [file] ...
neqn [file] ...
checkeq

🦋 DESCRIPTION 🦋

okay so here's the lore. eqn is a troff(1) preprocessor for typesetting mathematics on a phototypesetter, and neqn does it on terminals. The usage is almost always:

eqn file ... | troff
neqn file ... | nroff

If no files are specified, these programs read from the standard input. slay. 💖

A line beginning with .EQ marks the start of an equation; the end of an equation is marked by a line beginning with .EN. Neither of these lines is altered, so they may be defined in macro packages to get centering, numbering, etc. It is also possible to set two characters as delimiters; subsequent text between delimiters is also treated as eqn input. Delimiters may be set to characters x and y with the command-line argument -dxy or (more commonly) with delim xy between .EQ and .EN. The left and right delimiters may be identical. Delimiters are turned off by delim off. All text that is neither between delimiters nor between .EQ and .EN is passed through untouched. periodt. ✨

The program checkeq reports missing or unbalanced delimiters and .EQ/.EN pairs. It's giving quality control, and honestly we love that for us. 🫶

Quick flag translation for the group chat:

• -dxy — sets the two delimiters to characters x and y.
• -fn — the command-line global font change, matching gfont n.
• -sn — the command-line global size change, matching gsize n.
• -pn — changes the normal subscript/superscript shrink; normally they're reduced by 3 point sizes from the previous size.

Tokens within eqn are separated by spaces, tabs, newlines, braces, double quotes, tildes or circumflexes. Braces {} are used for grouping; generally speaking, anywhere a single character like x could appear, a complicated construction enclosed in braces may be used instead. Tilde ~ represents a full space in the output, circumflex ^ half as much. iykyk. 💫

Subscripts and superscripts are produced with the keywords sub and sup. Thus x sub i makes xi, a sub i sup 2 produces ai, and e sup {x sup 2 + y sup 2} gives ex2+y2. the way that math math-ed. 😭

Fractions are made with over: a over b yields _.

sqrt makes square roots: 1 over sqrt {ax sup 2 +bx+c} results in __________ .

The keywords from and to introduce lower and upper limits on arbitrary things: lim∞Σxi is made with lim from {n-> inf } sum from 0 to n x sub i.

Left and right brackets, braces, etc., of the right height are made with left and right: left [ x sup 2 + y sup 2 over alpha right ] ~=~1 produces ⎣x2+__⎦=1. The right clause is optional. Legal characters after left and right are braces, brackets, bars, c and f for ceiling and floor, and "" for nothing at all (useful for a right-side-only bracket). iconic bracket behavior. 🌈

Vertical piles of things are made with pile, lpile, cpile, and rpile: pile {a above b above c} produces b with c tucked underneath in the original's little stack. There can be an arbitrary number of elements in a pile. lpile left-justifies, pile and cpile center, with different vertical spacing, and rpile right justifies. pile supremacy. 🎀

Matrices are made with matrix:

matrix { lcol { x sub i above y sub 2 } ccol { 1 above 2 } } produces xi 1.
                                                                       y2 2

In addition, there is rcol for a right-justified column.

Diacritical marks are made with dot, dotdot, hat, tilde, bar, vec, dyad, and under: x dot = f(t) bar is x=f(t), y dotdot bar ~=~ n under is y=n, and x vec ~=~ y dyad is x=y. the accents ate. 💅

Sizes and font can be changed with size n or size ±n, roman, italic, bold, and font n. Size and fonts can be changed globally in a document by gsize n and gfont n, or by the command-line arguments -sn and -fn.

Normally subscripts and superscripts are reduced by 3 point sizes from the previous size; this may be changed by the command-line argument -pn. tiny text rights. 🦋

Successive display arguments can be lined up. Place mark before the desired lineup point in the first equation; place lineup at the place that is to line up vertically in subsequent equations. alignment is self-care. ✨

Shorthands may be defined or existing keywords redefined with define: define thing % replacement % defines a new token called thing which will be replaced by replacement whenever it appears thereafter. The % may be any character that does not occur in replacement.

Keywords like sum (Σ) int (∫) inf (∞) and shorthands like >= (≥) -> (−>) and != (≠) are recognized. Greek letters are spelled out in the desired case, as in alpha or GAMMA. Mathematical words like sin, cos, log are made Roman automatically. troff(1) four-character escapes like \(bs ( ) can be used anywhere. Strings enclosed in double quotes "..." are passed through untouched; this permits keywords to be entered as text, and can be used to communicate with troff when all else fails. when all else fails, quote it and pray. 🙈

🌈 SEE ALSO 🌈

• troff(1), tbl(1), ms(7), eqnchar(7)
• B. W. Kernighan and L. L. Cherry, Typesetting Mathematics—User's Guide
• J. F. Ossanna, NROFF/TROFF User's Manual

💀 NOTES 💀

To embolden digits, parens, etc., it is necessary to quote them, as in bold "12.3". do not forget the quotes, bestie, or the bold will not hit the way you want. 😭

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That's the whole manual, and yes, it ate. This page is from Heirloom Documentation Tools, dated 12/12/05 — source/version and date, signed off with glitter and good vibes. 💖✨🎀