Commit | Line | Data |
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c9528a00 C |
1 | .NH |
2 | Photocomposition | |
3 | .PP | |
4 | Photocomposition techniques | |
5 | can be used to solve some of the problems of typesetting mathematics. | |
6 | A phototypesetter is a device which exposes | |
7 | a piece of photographic paper or film, placing characters | |
8 | wherever they are wanted. | |
9 | The Graphic Systems phototypesetter[2] on the | |
10 | .UC UNIX | |
11 | operating | |
12 | system[3] works by shining light through a character stencil. | |
13 | The character is made the right size by lenses, | |
14 | and the light beam directed by fiber optics | |
15 | to the desired place on a piece of photographic paper. | |
16 | The exposed paper is developed and typically used | |
17 | in some form of photo-offset reproduction. | |
18 | .PP | |
19 | On | |
20 | .UC UNIX , | |
21 | the phototypesetter is driven by a formatting program called | |
22 | .UC TROFF | |
23 | [4]. | |
24 | .UC TROFF | |
25 | was designed for setting running text. | |
26 | It also provides all of the facilities that one needs for | |
27 | doing mathematics, such as | |
28 | arbitrary horizontal and vertical motions, | |
29 | line-drawing, size changing, | |
30 | but the syntax for describing these special operations is | |
31 | difficult to learn, | |
32 | and difficult even for experienced users to type correctly. | |
33 | .PP | |
34 | For this reason we decided to use | |
35 | .UC TROFF | |
36 | as an ``assembly language,'' | |
37 | by | |
38 | designing a language for describing mathematical | |
39 | expressions, | |
40 | and compiling it into | |
41 | .UC TROFF . |