Template:Val/doc
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This template is used to easily present values in scientific notation, including uncertainty and/or units, as prescribed by Wikipedia's Manual of Style.
Introduction
Val specializes in numeric values, especially those with scientific notations, uncertainty notations, and those with measurement values with physical units. Because these expressions are covered by the Manual of Style, Val provides the stylized output for you, and keeps them from wrapping across lines.
Express a numeral:
{{val|123456.78901}}→ value, formated with gaps: 123456.78901, or with|fmt=commas→ 1,234.5678901.{{val|number|number}}→ value ± uncertainty, like 123,478±56{{val|number|(number)}}→ value(uncertainty), like 12,345(56).{{val|number|number|number}}→value +uncertainty
−uncertainty like 1234+56
−78
Express a measurement value: {{val|4|ul=m2}} → 4 m2. The m2 is a "unit code" that Val uses to lookup the link to the unit's article, and the formatting of the unit symbol. Val links the units to the page it has on file for them. See {{Val/list}}.
There are a large number of unit codes that Val understands and keeps "up to code". A unit code is the just abbreviated unit name, but these can get quite involved for a compound or composite unit, with "multipliers" or "dividers". See Module:Val/units.
Some unit-code flexibility is provided by having four parameters to work the unit-code system: whether to link one or not, (see Overlinking), and whether to link the numerator or denominator of a unit ratio separately.
{{val|number|ul=unit code}}→ number symbol, such as 9.8 km2{{val|number|u=unit code}}→ number symbol{{val|number|u=unit code|upl=unit code}}→ number symbol/symbol, such as 9.8 gal/min{{val|number|ul=unit code|up=unit code}}→ number symbol/symbol, such as 9.8 pc/year
To bypass the unit code system, if |u= does not recognize your unit code, it will accept any wikitext and render it as usual.
{{val|5.4|u=[[kg]]⋅[[meter|m]]/s<sup>2</sup>}}→ 5.4 kg⋅m/s2{{val|7.6|u=[[metre per second squared|m/s<sup>2</sup>]]}}→ 7.6 m/s2
See Module:Val/units for how to add units to the unit code system.
Sometimes a number and unit code is not enough. A prefix or suffix are also available, |p= and |s=.
{{val|7600|p=>|s=<|u=C⋅Ga}}→ >7600 C⋅Ga<{{val|7600|p=<span style="color:green"><sup>|s=</span></sup>|u=C}}→ 7600 C
See {{val/testcases}} to learn the val parameters by a example. It's comprehensive, and there's over 100 examples.
Arguments
Template:More Val takes three unnamed parameters. The first is always the numeric value. When the second and third are numbers they become the various uncertainty notations, but the second unnamed parameter can also serve to grammatically join the first and third numbers.
Val clears surrounding spaces in its unnamed parameters.
| 1st | The numeric basis of the value. Defaults to 100.
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| 2nd (Or see below.) |
Uncertainty in either format.
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| 3rd | Asymmetric uncertainty.
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|e=
|
Exponential.
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|fmt=
|
Format strings of digits. Accepts |fmt=commas for the integer part, but commas ignores the fractional part. Defaults to gaps, except for four digits. Four digits accept |fmt=gaps.
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|u= or |ul= |
The unit code. Val adds a space and the unit.
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|up= or |upl= |
A unit code, but Instead of a space Val adds a slash and the unit, a "per" unit (the denominator), to form a ratio.
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|p= |
Prefix. Non-spaced, but accepts markup.
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|s= |
Suffix. Non-spaced, but accepts markup.
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|end= |
Add something between the base number and what follows.
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|errend= or |+errend= and |-errend= |
Appends something after an uncertainty.
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| 2nd | A conjunction to join two numbers. Useful for ranges, grammatical output, etc.
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|us= or |ups= |
Alternative unit code for sorting. {{val|12|u=kB|us=kiB}} will display 12 kB but sort as 12 kiB.
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|long scale= |
Usually a unit is the short ton and billion means 1×109. But there are long versions of these units and others. Use |long scale=on to assign your unit to the long scale instead. The unit code's link will change and it will sort differently in tables. "See Long and short scales".
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|nocategory= |
If set to any value, errors in the use of this template will not cause the page to be added to the Pages with incorrect formatting templates use category. This is useful for documentation and test pages that do not need to be fixed. |
Errors
There is strict checking on the validity of arguments; any incorrect use will result in an error, which is displayed using {{FormattingError}}. Pages that contain incorrect use of this template will show up on Category:Pages with incorrect formatting templates use.
Format of numbers
{{Val}} produces formatting compliant with Wikipedia's Manual of Style.
The MOS recommends that numbers either be delimited using thin spaces either side of the decimal, or commas to the left and no delimiters to the right. Articles should be consistent with respect to the style of delimiting. The template defaults to the former style, this can be adjusted using |fmt= (see above).
Sorting
A hidden sort key is added to the output for sorting in sortable tables. The sort key is based on the main value (parameter |1=) and, if used, the exponent for the power of 10 (parameter |e=) and/or units (parameters |u=, |ul=, |up= and/or |upl=). Where necessary, units are converted to base SI units for the purpose of the sort key, which is produced by {{ntsh}}. Several units are covered; see § How to add units for those which are not. To omit the sort key use |sortable=off.
Examples
- Number
{{val|1234567.1234567}} → 1234567.1234567
{{val|.1234567}} → 0.1234567
{{val|+1234567}} → +1234567
{{val|-1234567}} → −1234567
- Uncertainty
{{val|1.234|0.005}} → 1.234±0.005
{{val|1.234|+0.005|-0.006}} → 1.234+0.005
−0.006
{{val|1.234|(5)}} → 1.234(5)
- Units
{{val|1.234|u=m}} → 1.234 m
{{val|1.234|u=m2}} → 1.234 m2
{{val|1.234|ul=m}} → 1.234 m
{{val|123.4|ul=USgal}} → 123.4 US gal
{{val|12.34|ul=mpgimp}} → 12.34 mpg‑imp
{{val|12.34|u=deg}} → 12.34°
{{val|1.234|0.005|u='}} → 1.234′±0.005′
{{val|1.234|+0.005|-0.006|u="}} → 1.234″+0.005″
−0.006″
- Exponents
{{val|1.234|ul=m|e=5}} → 1.234×105 m
{{val|1.234|0.056|e=7}} → (1.234±0.056)×107
{{val|1.23456|+0.00007|-0.00008|ul=m/s|e=-9}} → 1.23456+0.00007
−0.00008×10−9 m/s
{{val|1.234|0.056|ul=psi|e=7}} → (1.234±0.056)×107 psi
{{val|1.234|(5)|e=-2}} → 1.234(5)×10−2
- Prefix/suffix
{{val|12.34|p=Δ }} → Δ 12.34
{{val|12.34|p=≅|u=%}} → ≅12.34%
{{val|12.34|0.25|s=%}} → 12.34±0.25%
- Numerator/Denominator
{{val|1.234|e=7|ul=W|up=m2}} → 1.234×107 W/m2
- Even more examples
See the testcases at {{val/testcases}}.
Performance impact
Val is now a module. Modules have excellent performance compared to the normal template that uses parser functions.
Performance data is reported by MediaWiki software in the HTML page source of every page, and a very similar report is available on any preview page, below the edit box, titles "Parser profile data".
For uses in any page, even long list articles, Module:Val will have very little impact on page-load times.
How to add units
Add the unit to Module:Val/units. Val defaults to looking up units at {{Convert}}, but Module:Val/units overrides that default.
Note these points about composite units before adding units:
- For composite units you should probably link the whole, not individual units. For example the line you add would say
m.s-1 [[Metre per second|m⋅s<sup>−1</sup>]]linking to Metre per second, notm.s-1 [[Metre|m]]⋅[[Second|s]]<sup>&minus1</sup>.
- List of common physics notations has many examples of composite units that have their own page.
- The val user can compose their own divisor unit from an existing unit, for example writing
{{val|99|ul=m|upl=s}}to render their own "99 m/s" with two links:mto Meter andsto Second. - The val user can compose their own multiplier units by using the
endparameter to prepend a string. For example, in a geology article, to prepend "Ma", to the unit in 333 14C yr BP, use{{val|333|ul=uBP|end= [[megaannum|Ma]]}}→ 333 Ma 14C yr BP". (Theendparameter accepts wikitext, so it can be linked.)
After adding a unit, you can ensure that it sorts correctly in a table, especially if there are ten or twenty variations that differ only by an SI prefix. (See § Sorting above.)
FAQ and comments
- Q: Why should I use Val?
- A1: Val formats numbers:
- inserts spaces between groups of digits, approximating SI standards
- properly formats uncertainties in measurements and significant digits, providing a ± character, etc.
- properly formats exponents of 10 and scientific notation
- replaces "-" (hyphen) with a "−" (minus sign)
- A2: Val preserves spacing:
- It makes sure the value does not wrap at the end of a line, so that it can always be read as a single value on one line in the text.
- It spaces the various parts of the value where they should be
- A3: Configuring Val gives you your own code for automating the markup for, and a link to, any units in the entire Encyclopedia.
- A4: Val helps make Wikipedia more consistent. It adheres to the Wikipedia Manual of Style for numbers. Updates to the MoS can be applied to this template, and result in automatic modification on values that use it. All this makes sure all values on all pages have the same look and feel because they will all use the same spacing, font size, positioning, etc, and makes updating and checking by the bots easier because they can recognize a value for what it is.
- Q: Why not use <math>?
- A: For the same reasons HTML might be preferred over TeX:
- Because the font in math tags differs both in face and size from the prose, which can disturb the layout of a page when used inline with the prose.
- You cannot cut and paste a bitmap image rendered by the Latex.
- Images are slower to load and use more bandwidth, which is especially bad for the mobile version of Wikipedia.
- <math> does not automatically easily align to the Manual of Style for numbers.
- Q: Are there any known issues with Val?
- A1: This template is now a new Lua module as of Aug 6, 2015. Technically, there is no good reason not to try Val.
- A2: Issues are solved rapidly by an active set of responsive template coders. See the talk page.
- Q: How should I use Val?
- A1: Val probably already has your unit on its current list. If not, add your own unit there.
- A2: To avoid over linking switch from
|ul=to|u=and from|upl=to|up=. - A3: Any time you have a unit to link or a table to sort, Val already setup with that unit's link and sorting value.
- A3: Use Val along with {{Convert}}. See how to add units to Convert.
- A4: Where consistent styling of long list articles, with many hundreds or thousands of numbers or units is needed.
See also
