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Minor quibble: having a non-integral “number” of spaces was not a TeX innovation; Knuth was just reproducing standard practice of fine typography. Using variabl

by svat 7y ago

Minor quibble: having a non-integral “number” of spaces was not a TeX innovation; Knuth was just reproducing standard practice of fine typography. Using variable-width separators (TeX “glue”) is exactly how human typesetters did it for centuries. So it's not quite the right perspective to consider anything “a holdover from the typewriter era”, because that had never been typographical practice in the first place — in fact the typewriter practice approximated fine typography (rounding up the larger inter-sentence space to 2), rather than the other way around (see my top-level comment below/above). In fact, with TeX's standard settings, the inter-sentence space has the same natural width as the inter-word space; it's just that when justifying paragraphs it stretches more (3x) and shrinks less (0.33x) than the inter-word space — the net effect is that inter-sentence spaces are (usually) subtly larger.

peterkelly 7y ago
Good points, thanks for clarifying this. We had a really long period of time where printed material was produced by professional typesetters, followed by a much shorter period where people started producing documents using typewriters and computers with software that worked with fixed-width characters. Then with with TeX, proportionally spaced fonts, and the desktop publishing revolution we got that ability back. For some reason there are a lot of people thinking in terms of typewriters and 1980s-era word processors when talking about sentence spacing, which seems quite odd.
jfk13 7y ago
> with TeX's standard settings, the inter-sentence space has the same natural width as the inter-word space That's not quite accurate; the inter-sentence space does have a slightly larger natural width as well as more stretchability. It's right there in Chapter 12 of The TeXbook: > "Plain TeX puts extra space at the end of a sentence; furthermore, it automatically increases the stretchability (and decreases the shrinkability) after punctuation marks." Specifically, in the default cmr10 font, a normal inter-word space is 3.33333pt, and an end-of-sentence space has an additional 1.11111pt (before any stretch or shrink is applied).
- svat 7y ago
  Oh oops, sorry about that, thanks for the correction — was doing something custom recently, and got myself confused. So just for completeness: at the default settings, for cmr10 (a 10pt font), • inter-word space has natural width 3.33333pt, stretchability 1.66666, shrinkability 1.11111. • inter-sentence space has natural width 4.44444pt, stretchability 4.99997, shrinkability 0.37036. So the net-effect is that, for example: • for a line set at natural width: inter-word space is 3.33333pt and inter-sentence space is 4.44444pt (so it's 33% larger) • for a loose line, stretched by ∛2 (badness 200, the maximum without complaining with the default setting of \tolerance): inter-word space is 5.43319pt, inter-sentence space is 10.7440pt (so it's 97% larger) • for a tight line, shrunk by ∛2 (badness 200, the maximum without complaining with the default setting of \tolerance): inter-word space is 1.93342pt, inter-sentence space is 3.97782pt (so it's 106% larger) So only for very loose or tight lines does the inter-sentence space get close to "two spaces".

by svat 7y ago

peterkelly 7y ago

Good points, thanks for clarifying this. We had a really long period of time where printed material was produced by professional typesetters, followed by a much shorter period where people started producing documents using typewriters and computers with software that worked with fixed-width characters. Then with with TeX, proportionally spaced fonts, and the desktop publishing revolution we got that ability back. For some reason there are a lot of people thinking in terms of typewriters and 1980s-era word processors when talking about sentence spacing, which seems quite odd.

jfk13 7y ago

> with TeX's standard settings, the inter-sentence space has the same natural width as the inter-word space That's not quite accurate; the inter-sentence space does have a slightly larger natural width as well as more stretchability. It's right there in Chapter 12 of The TeXbook: > "Plain TeX puts extra space at the end of a sentence; furthermore, it automatically increases the stretchability (and decreases the shrinkability) after punctuation marks." Specifically, in the default cmr10 font, a normal inter-word space is 3.33333pt, and an end-of-sentence space has an additional 1.11111pt (before any stretch or shrink is applied).

svat 7y ago
Oh oops, sorry about that, thanks for the correction — was doing something custom recently, and got myself confused. So just for completeness: at the default settings, for cmr10 (a 10pt font), • inter-word space has natural width 3.33333pt, stretchability 1.66666, shrinkability 1.11111. • inter-sentence space has natural width 4.44444pt, stretchability 4.99997, shrinkability 0.37036. So the net-effect is that, for example: • for a line set at natural width: inter-word space is 3.33333pt and inter-sentence space is 4.44444pt (so it's 33% larger) • for a loose line, stretched by ∛2 (badness 200, the maximum without complaining with the default setting of \tolerance): inter-word space is 5.43319pt, inter-sentence space is 10.7440pt (so it's 97% larger) • for a tight line, shrunk by ∛2 (badness 200, the maximum without complaining with the default setting of \tolerance): inter-word space is 1.93342pt, inter-sentence space is 3.97782pt (so it's 106% larger) So only for very loose or tight lines does the inter-sentence space get close to "two spaces".