Description
Use that policy for identical values, preserve a +360 difference as full width, and otherwise wrap the difference modulo 360.
Longitude is an angular coordinate with a seam and equivalent values separated by full turns. Interval direction, endpoint inclusion, and half-turn policy must be fixed before comparing or averaging longitudes.
Use that policy for identical values, preserve a +360 difference as full width, and otherwise wrap the difference modulo 360.
When to use this tool
Use Geography: Longitude Interval Span With Wrap when you need a longitude normalization, interval, or seam-policy calculation.
How to use the tool and how it works
- Enter westDegrees, eastDegrees, equalEndpoints. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read result. Expand result to inspect the returned fields.
Require west and east longitudes within [-180, 180] and empty or full equal-endpoint policy. Use that policy for identical values, preserve a +360 difference as full width, and otherwise wrap the difference modulo 360.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| westDegrees | West Degrees Unit: deg. | Required. Finite number. |
| eastDegrees | East Degrees Unit: deg. | Required. Finite number. |
| equalEndpoints | Equal Endpoints | Required. Text; one of "empty", "full". Implementation limit: 8192 Unicode code points and 16384 UTF-16 code units. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| result | Object containing the calculated members; expand to inspect the fields below. | Required. Object. |
| result.spanDegrees | Span Degrees | Calculated result member: number. |
| result.crossesSeam | Crosses Seam | Calculated result member: boolean. |
{
"input": {
"westDegrees": 170,
"eastDegrees": -170,
"equalEndpoints": "empty"
},
"output": {
"result": {
"spanDegrees": 20,
"crossesSeam": true
}
}
}Limitations and assumptions
- A -360 difference yields zero, unlike +360. crossesSeam requires east below west and a positive span; endpoint policy applies to identical numeric endpoints and does not infer political or geometric boundaries.
- Outputs are nested inside result. 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 full spherical or ellipsoidal geometry method for routes and areas. Retain an explicit seam and endpoint policy when splitting, sorting, or averaging geographic data.
References
Similar or alternative tools
- Longitude Cell Half Open Membership
Test membership in the west-inclusive, east-exclusive interval, using a union across the seam when west exceeds east.
- Longitude Sector Membership
Require longitudes and sector endpoints within [-180, 180], normalize 180 to -180, and test the direct or seam-crossing interval with independent endpoint-inclusion flags.