Description
Return a decade index relative to a supplied year origin.
Date labels and intervals depend on origins, endpoint inclusion and calendar versus elapsed-time conventions. Numeric serial periods and local token formats can represent useful bookkeeping without resolving a real instant or official fiscal rule.
Return a decade index relative to a supplied year origin.
When to use this tool
Use Calendar Decade Explicit Origin Index when checking a supplied date-label, duration or interval convention.
How to use the tool and how it works
- Enter year, origin. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read index, firstYear. Use the output convention below.
Return a decade index relative to a supplied year origin. index = floor((year-origin)/10); firstYear = origin+10*index.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| year | Year | Required. Safe integer. |
| origin | Origin | Required. Safe integer. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| index | Position under the stated indexing convention; inspect any missing-value sentinel. | Required. Safe integer. |
| firstYear | First Year | Required. Safe integer. |
{
"input": {
"year": 2026,
"origin": 2000
},
"output": {
"index": 2,
"firstYear": 2020
}
}Limitations and assumptions
- Negative indexes are allowed; this origin-based grouping differs from automatically named historical decades.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Use a complete date/time implementation and the applicable calendar policy for actual scheduling and interval interpretation.
References
Similar or alternative tools
- Calendar Semi Year Period Index
Return a calendar half-year label.
- Fiscal Period Label Explicit Start Month
Return fiscal start year and period from an explicit start month.