Template:Val
.svg){kind=link}
| Warning | This template is used on 5,000+ pages and changes may be widely noticed. Test changes in the template's /sandbox or /testcases subpages, or in your own user subpage. Consider discussing changes on the talk page before implementing them. |
| File:Lua-Logo.svg | This template uses Lua: |
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[change]
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, formatted 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, such as 9.8 km2{{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=</sup></span>|u=C}}→ 7600 C
See {{val/testcases}} to learn the val parameters by an example. It is comprehensive, and there are over 100 examples.
Arguments[change]
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 or |1= |
A number in decimal point notation or in e notation. The main basis of the Val expression.
|
|fmt=
|
By default, numbers are formatted with gaps separating groups of three digits in both integer and fractional part. However, by default, four-digit integers are not formatted; use |
|end= |
Put something at the end of the main number (before anything else that might follow).
|
2nd or |2= |
Uncertainty in either format.
|
3rd or |3=
|
Asymmetric uncertainty.
|
|errend= or |+errend= and |-errend= |
Appends something after an uncertainty.
|
|u= or |ul= |
The unit code. Val adds a space and the unit.
|
|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.
|
|p= |
Prefix the entire Val expression. Non-spaced, but accepts markup.
|
|s= |
Suffix the entire Val expression. Non-spaced, but accepts markup.
|
|e=
|
Exponent. Val alternatively accepts e notation in the first parameter; these are mutually exclusive (see "1st" argument above).
|
|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".
|
|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[change]
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.
Val checks for unsupported parameters and gives a relatively subtle warning if found. See tracking category to track any of these improper usages on existing on the wiki. Hold the mouse over "warning" to see details. Here is what warnings look like:
{{val|1.23|exp=6|u=m/s}}→ 1.23 m/swarning{{val|1.23|us=kbit/s}}→ 1.23warning{{val|1.23|.05|.04|.03|u=m/s}}→ 1.23+0.05
−0.04 m/swarning
Format of numbers[change]
{{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[change]
The sort key for each sortable unit is visible at Template:Val/list.
Here is a live example showing the minimal markup for a sortable table:
{| class="sortable"
! Val sort test
|-
| {{val|3|ul= Mm }}
|-
| {{val|4e6|u= m }}
|-
| {{val|1|u= km }}
|-
| {{val|5e3|u= m }}
|-
| {{val|2|u= m }}
|}
|
|
A sort value relates to a Val expression as follows.
- The numeric value is a starting point.
- If the unit has an SI Prefix, that order of magnitude is applied.
- The value of the unit from its own system of units is applied.
- If the unit is composite, each subunit is multiplied or divided per their dimension.
- The result is passed to {{ntsh}} which applies a normalization formula.
- The output of {{ntsh}} is added (behaviorally only, i.e. "hidden") into the table as usual, via the data-sort-value attribute of a table.
More example expressions[change]
- Number
{{val|1234567.1234567}} → 1234567.1234567
.{{val| 1234567.1234567 }}. → .1234567.1234567.
{{val|.1234567|fmt=commas}} → 0.1234567
{{val|+1234567|fmt=commas}} → +1,234,567
{{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″
{{val|1.234|u=%}} → 1.234%
{{val|1.234|end= [[m/s]]}} → 1.234 m/s
{{val|12.34|u=degC}} → 12.34 °C
{{val|12.34|u=K}} → 12.34 K
- Exponents
{{val|1.234e5|ul=m}} → 1.234×105 m
{{val|1.234|ul=m|e=5}} → 1.234×105 m
{{val|1.234e7|0.056}} → (1.234±0.056)×107
{{val|1.234|0.056|e=7}} → (1.234±0.056)×107
{{val|1.23456e-9|+0.00007|-0.00008|ul=m/s}} → 1.23456+0.00007
−0.00008×10−9 m/s
{{val|1.23456|+0.00007|-0.00008|ul=m/s|e=-9}} → 1.23456+0.00007
−0.00008×10−9 m/s
{{val|1.234e7|0.056|ul=psi}} → (1.234±0.056)×107 psi
{{val|1.234|0.056|ul=psi|e=7}} → (1.234±0.056)×107 psi
{{val|1.234e-2|(5)}} → 1.234(5)×10−2
{{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
- Repeating digits
{{val|1.2|end={{overline|34}}|e=7|ul=W|up=m2}} → 1.234×107 W/m2
- Even more examples
See the testcases at {{val/testcases}}.
Performance impact[change]
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.
FAQ and comments[change]
- Q: Why should I use Val?
- A1: Val formats numbers:
- inserts spaces between groups of digits, meeting MoS standards,
- formats standard uncertainties in measurements, providing a ± character, correct spacing, and correct alignment,
- 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 overlinking, 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.