[Tex/LaTex] The shortcuts for measurement units: cm and dm

unit-of-measure

I have to write a math book and I'm using often the following measurement units: centimeter (cm), decimeter (dm). Can you provide me the shortcut which will output cm and dm. For meter(m) I've found the following shortcut \meter -> m.

Best Answer

When you use siunitx the shortcuts are already there. \dm and \cm are already provided: see page 36 of siunitx manual (version from 2016/03/01). Shorter shortcuts you will not find. (There are two packages siunits and siunitx, I prefer the latter.)

Related Solutions

[Tex/LaTex] Which measurement units should one use in LaTeX

There are no hard-and-fast rules, but here's a short list of guidelines:

"1em" can be considered a horizontal length and "1ex" a vertical one, so use them accordingly but mix and match as you need (they are horizontal and vertical arbitrarily, but usually you hear people talk about "1em" is the width of an "m" — usually false — and "1ex" is the height of an "x" — usually true). I usually consider 1em to be about the same size as the font size in points.
em and ex are relative lengths, so they're better for designing around text; like you say, an indent of 2em will work whether the fontsize is 9pt or 12pt.
Things that are of fixed size (such as the page size) should be defined with fixed units, of course.
When things should be relative, it will often make more sense to define them in terms of the page design. For example, width=0.5\linewidth might make more sense than width=5cm for a figure.
Watch out for the pt unit! In TeX, 1pt is 1/72.27in, whereas the more common "PostScript point" used by most other software is 1/72in which in TeX is 1bp. If you're dealing with other programs and need your lengths exact, use bp or use standard cm or in measurements.
Remember that TeX uses fixed point arithmetic, so there are precision problems when you hit around five significant figures. E.g.,
```
  \newlength\x
  \x=1in
  \showthe\x
```
gives
```
  > 72.26999pt.
```

[Tex/LaTex] Globally redefining 1 pt to 1/72 in (PostScript point) and other similar changes

The answer is simply: no, you cannot change the meaning of pt, dd, et cetera.

The only unit you can change is the pdftex extension unit px, which can be altered by setting \pdfpxdimen.

The supplementary question: TeX actually calculates in units of 1/65536 'pt'. As a result, the distance pt is never explicitly defined as a physical unit until it is implicitly converted into one at the final output stage. In DVI (either original TeX or pdftex/xetex/luatex in DVI mode), this is not easy to change at all, because the code assumes a one-on-one relationship between its own units and the DVI units.

In pdftex's PDF mode it is somewhat easier because a correction is needed there anyway. You should look at the functions divide_scaled() and round_xn_over_d(), but (of course) you will not need them where they are now, and on the other hand you may need the inverse of those functions in places where they are now not. All in all, this sounds like a mad undertaking to me.

The other units are quite a lot easier: all are declared relative to pt. Search for set_conversion in tex.web, and by adjusting the fractions that are specified there, you can change their behaviour throughout.

Best Answer

Related Solutions

[Tex/LaTex] Which measurement units should one use in LaTeX

[Tex/LaTex] Globally redefining 1 pt to 1/72 in (PostScript point) and other similar changes

Related Question