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===Expressing Physical quantities===
A physical quantity is number plus unit, and should not be split. A simple way to do this follows - define your own macro:
<texcode>
\define[3]\physicalquantityle{\hbox{#1 \times \lunit{10^#2 #3}}}
</texcode>
You can then write
\physicalquantityle{number}{exponent}{unit}
This seems to give better results than any other way I have found of combining digits and units.
The full range of variants allow expression of physical quantities with and without exponents, with units in long form or not:
<texcode>
\define[2]\physicalquantity{\hbox{\unit{#1 #2}}}
% \physicalquantity{number}{unit} -- gives short form of unit
\define[2]\physicalquantityl{\hbox{\lunit{#1 #2}}}
% \physicalquantityl{number}{unit} -- gives long form of unit
\define[3]\physicalquantitye{\hbox{#1 \times \lunit{10^#2 #3}}}
% \physicalquantitye{number}{exponent}{unit} -- gives short form of unit
\define[3]\physicalquantityle{\hbox{#1 \times \lunit{10^#2 #3}}}
% \physicalquantityle{number}{exponent}{unit} -- gives long form of unit</texcode>
</texcode>
You can also do ranges of units, that are otherwise messy to code up on an individual basis
<texcode>
\define[3]\physicalquantityspread{\hbox{#1\endash \lunit{#2 #3}}}
</texcode>
You can then write:
\physicalquantityspread{start}{end}{unit}
[[Category:Physics]]
no edit summary
The units module comes with ConTeXt's default distribution, and can be accessed via <cmd>usemodule</cmd>[units].
However, in MkIV we have integrated an upgrade to this mechanism so if you're using that version you might want to skip this first part. Additional documentation about units in MkIV is available from the [[http://www.pragma-ade.com/general/manuals/units-mkiv.pdf Units manual]]
The following is copied from the source file [[source:m-units.tex|m-units.tex]] and only slightly modified:
External link:
[[httphttps://www.unceasyunitconverter.educom/~rowlett/units/index.html How Many? A Dictionary of Units of MeasurementEasy Unit Converter]]
* Prefixes: <cmd>Atto</cmd> a, <cmd>Femto</cmd> f, <cmd>Pico</cmd> p, <cmd>Nano</cmd> n, <cmd>Micro</cmd> μ, <cmd>Milli</cmd> m, <cmd>Centi</cmd> c, <cmd>Deci</cmd> d, <cmd>Hecto</cmd> h, <cmd>Kilo</cmd> k, <cmd>Mega</cmd> M, <cmd>Giga</cmd> G, <cmd>Tera</cmd> T, <cmd>Peta</cmd> P, <cmd>Exa</cmd> E (missing: <cmd>Zetta</cmd> Z, <cmd>Yotta</cmd> Y, <cmd>Zepto</cmd> z, <cmd>Yocto</cmd> y)
* Informatics: <cmd>Baud</cmd>, <cmd>Bit</cmd>, <cmd>Byte</cmd>
* some old dutch (not listed)
===Define a new unit===
<context source="yes">
\usemodule[units]
\unit[Mynewunit]{Nu}{New Unit}
10 \Mynewunit
</context>
===Using the built-in command===
\unit{123.22e-3 km/s}
</texcode>
ConTeXt will take care of spacing and formatting. The parser is fairly flexible, and the following all work and give the same output.
{|
! width="45%"|
! width="10%"|
! width="45%"|
|-
| <texcode>
\unit{10 kg}
\unit{10kg}
\unit{10 kilo gram}
\unit{10 kilogram}
\unit{10 Kilo Gram}
\unit{10 KiloGram}
</texcode>
|
|<context mode=mkiv>
\starttext
\startlines
\unit{10 kg}
\unit{10kg}
\unit{10 kilo gram}
\unit{10 kilogram}
\unit{10 Kilo Gram}
\unit{10 KiloGram}
\stoplines
\stoptext
</context>
|}
The command works in text as well as in math mode and spaces are normally ignored. You can define your own command:
In due time there will be a few more options. Numbers are formatted cf the digits mechanism (not discussed here).
[[Category:Math]]
[[Category:Modules]]
