Description
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.
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.
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.
When to use this tool
Use Longitude Sector Membership when you need a longitude normalization, interval, or seam-policy calculation.
How to use the tool and how it works
- Enter longitudeDegrees, startDegrees, endDegrees, includeStart, includeEnd. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read inside, crossesDateline. Inspect inside, crossesDateline before interpreting the associated values.
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.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| longitudeDegrees | Longitude Degrees | Required. Finite number. |
| startDegrees | Start Degrees | Required. Finite number. |
| endDegrees | End Degrees | Required. Finite number. |
| includeStart | Include Start | Required. Boolean. |
| includeEnd | Include End | Required. Boolean. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| inside | Inside | Required. Boolean. |
| crossesDateline | Crosses Dateline | Required. Boolean. |
{
"input": {
"longitudeDegrees": 175,
"startDegrees": 170,
"endDegrees": -170,
"includeStart": true,
"includeEnd": false
},
"output": {
"inside": true,
"crossesDateline": true
}
}Limitations and assumptions
- Equal normalized endpoints represent only a singleton when both boundaries are included, otherwise an empty sector; they never mean the whole world. The result checks angular membership rather than actual geographic regions.
- 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 Arc Complement
Return the smaller of their absolute difference and its 360-degree complement as shortArcDegrees, and 360 minus that result as longArcDegrees.