Bản mẫu:Inflation/doc

This template calculates inflation based on several inflation index data sets. The template uses an identification code for an inflation index (usually a country code), an original value, an original start_year and either a specific reference end_year or by default the latest currently available end year, and calculates the equivalent value from historical economic changes between the original and reference years. For example, this template calls the United States inflation table located in the sub-template Template:Inflation/US/dataset to perform the U.S. calculation.
Aside from a convenient way to calculate values from different specified time periods, this template allows a regularly automatically updated calculation of value based on the most recent available inflation data. Whenever inflation tables are updated, potentially annually, all articles using this template have their displayed values updated accordingly.

**Usage**
start_year
end_year
6=fmt=c
6=fmt=eq
7=cursign=X
The supported countries are listed below, with their index and available data periods:

**Parameters**
 index (parameter 1), required, an index code for one of several available inflation indexes.- value (parameter 2), required, original price or value from which to base the inflation calculation on. Will ignore any commas, but must not have a currency symbol.- start_year (parameter 3), required, original year from which to base the inflation calculation on. Must be a year available in the chosen inflation index. As an exception to this, if the current year is specified and no end_year is specified, the template will output value unchanged, as it can be assumed an inflation of zero.- end_year (parameter 4), optional, reference year for which to calculate inflation. Must be higher (later) than start_year, but not higher than the highest (most recent) year available in the chosen inflation index, and will default to the highest (most recent) available year if omitted.- digit sets the digits to which the value must be rounded. A negative value indicates rounding to an upper significant digit, and a positive value indicates a fractional digit including trailing zeros. Defaults to 0, i.e., without cents.- c will insert thousands separator commas into the calculated value.- eq will show an equivalent-to phrase, in the format, "equivalent to cursignend_value in end_year". Uses thousands separator commas.
** cursign will set the currency symbol to be shown. Only functions when eq is used. Can use advanced symbol formats, but can only precede the calculated value. Default is $.

**Examples**
   → -   → -   → -   → -   → -   → -   → -   → -   → -   → -   in  → 
It is possible to use the template in incorrect ways without producing error messages. Please read the warnings and appropriate uses of this template at the beginning of the template description.-   →  (Omitting the cursign parameter will show the $ symbol by default, which is the wrong currency symbol for British currency)-   → -   →  (Misleading time reference)-   →  (Misleading time reference)-   →  (Misleading time reference)-   → -   → -   →  (CPI is not for personal wealth of the wealthy – use GDP deflator instead)-   →  (CPI is not for personal wealth of the wealthy – use GDP deflator instead)-   → 
Entering invalid parameters or omitting required parameters will result in an error message and categorization into :Category:Pages with errors in inflation template.-   → nocat=y-   → nocat=y-   → nocat=y-   → nocat=y-   → nocat=y-   → nocat=y-   → nocat=y-   → -   → nocat=y-   → -   → -   → -   → 

**Tips & tricks**

**Currency conversion**
This template is currency agnostic, which means it doesn't convert between different currencies. Thus, if you wanted to know how much DM 1,000.00 marks in 1960 are worth nowadays, entering 5=r=2 would provide a result (r=2) still in marks, not in euros.
Consequently, if you need a result in another currency than the one in which the original value is stated, for now you must do the conversion manually, as in the following example which uses the defined conversion rate of € 1 = DM 1.95583:-   → 
A currency conversion template to ease these conversion tasks is planned. This section will be updated accordingly once it's developed.

**Rounding**
By default the values are calculated to the unit, as for all but very low values cents are undesirable. You can specify rounding with the r parameter which determines the number of decimals. To obtain cents use 2, but other values can be used, including negative ones: -3, for example, will round to the nearest thousand, -6 to the nearest million, and so on. It is advisable to avoid excessive precision; even if the start value is known to be exact, the template's result will not be because the inflation index tables are rarely accurate to more than about 1%, and a granularity of whole years is used.

**Very large results**
Very large results are expressed in scientific notation ("1.2E+14" instead of "120000000000000") which is normally not desirable. A workaround is to express the value to be inflated with fewer digits, adding a multiplier text such as "trillion" after the result, using the "Show preview" button as many times as needed, changing parameters until the best result is found:-   → -   → -   → -   → -   → -   → 
The following section provides an automated way of avoiding this trial and error scenario.

**Format price**
is a template specifically designed to display price values, both big and small, in a readable way. For example, instead of showing the whole of a huge number such as "953,783,409,856.12", it would show it as "953783409856.12", while small numbers have their cents part appearing as expected, "1234.5" being properly shown as "1234.5".-   → -   → -   → -   → 

**Documenting**
It's a good practice to provide a valid reference for the prices calculated with this template in articles where it's used. The template country was developed to ease this task. It accepts as its single parameter the same country codes used here, and will generate one or more appropriate footnotes. Typically, this is how a piece of text using it looks like:
Resulting in this converted code (notice the footnote link at the end):- In 1985 a unit cost on average $1,040. This is fmt=eq.US
The footnote thus generated appears whenever reflist or  is used in an article, usually in its "References" section. See below for the live example in this document's own References section, or click the above generated footnote to jump to it.

**Limitations**
# Currently it isn't possible to "de-inflate" a value to what it would have been in a previous year. If you need this functionality, please request it at the talk page. Adding it won't be difficult, but there's no point in doing so before someone actually needs it.
# Substitution isn't supported at all. Trying to Inflation would only result in a long sequence of embedded parser code without any direct benefit. If you need to obtain an inflated price only once, please use the special ExpandTemplates page then copy the result and paste it at the desired location.

**Developer documentation**
An inflation series represents templates in the following categories:- Template:Inflation/index- Template:Inflation/index/dataset- Template:Inflation/index/startyear- Template:Inflation/doc/index (Which is then displayed at Inflation/name/dataset as the documentation, and needs to refer to the original data source)
Modifications need to be made to:- Template:Inflation/fn- Template:Inflation/year
Current subpages:

**TemplateData**
{
	"params": {
		"value": {
			"aliases": 
				"2"
			,
			"label": "Value",
			"description": "Original price or value from which to base the inflation calculation on. Will ignore any commas.",
			"example": "1000",
			"type": "number",
			"required": true
		},
		"start_year": {
			"aliases": 
				"3"
			,
			"label": "Start year",
			"description": "Original year from which to base the inflation calculation on. Must be a year available in the chosen inflation index. As an exception to this, if the current year is specified and no 'End year' is specified, the template will output value unchanged, as it can be assumed an inflation of zero.",
			"example": "1975",
			"type": "number",
			"required": true
		},
		"index": {
			"aliases": 
				"1"
			,
			"label": "Index",
			"description": "An index code for one of several available inflation indexes. One of AU, AU-road, BD, CA, DE, IN, JP, PH, PK, UK, UK-GDP, US, US-GDP, ZAR.",
			"example": "US",
			"type": "string",
			"required": true
		},
		"end_year": {
			"aliases": 
				"4"
			,
			"label": "End year",
			"description": "Reference year for which to calculate inflation. Must be higher (later) than 'Start year', but not higher than the highest (most recent) year available in the chosen inflation index, and will default to the highest (most recent) available year if omitted.",
			"example": "2015",
			"type": "number"
		},
		"r": {
			"label": "Number of digits",
			"description": "Sets the digits to which the value must be rounded. A negative value indicates rounding to an upper significant digit, and a positive value indicates a fractional digit including trailing zeros. Defaults to 0.",
			"example": "1",
			"type": "number",
			"default": "0"
		},
		"fmt": {
			"label": "Format",
			"description": "\"c\" will insert thousands separator commas into the calculated value. \"eq\" will show an equivalent-to phrase, in the format, \"equivalent to (cursign)(end_value) in (end_year)\". Uses thousands separator commas.",
			"example": "eq",
			"type": "string"
		},
		"cursign": {
			"label": "Currency sign",
			"description": "Sets the currency symbol to be shown. Only functions when Format \"eq\" is used. Can use advanced symbol formats, but can only precede the calculated value. Default is $.",
			"example": "€",
			"type": "string",
			"default": "$"
		}
	},
	"paramOrder": 
		"index",
		"value",
		"start_year",
		"end_year",
		"r",
		"fmt",
		"cursign"
	,
	"format": "inline",
	"description": "This template calculates inflation based on several inflation index data sets. \n\nNote that this template defaults to calculating the inflation of Consumer Price Index values: staples, workers' rent, small service bills (doctor's costs, train tickets). For inflating capital expenses, government expenses, or the personal wealth and expenditure of the rich, the US-GDP or UK-GDP indexes should be used, which calculate inflation based on the gross domestic product (GDP) for the United States and United Kingdom, respectively."
}

**See also**
 Inflation/year- Inflation/fn- Format price- :Category:Currency templates- Inflation- Consumer price index- Consumer Price Index (United Kingdom)- Harmonised Index of Consumer Prices- Lists of country codes- List of circulating currencies- United States Consumer Price Index- GDP deflator

**References ==