Description
Normalize modulo 360, mapping the seam to +180 under positive policy or -180 otherwise.
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.
Normalize modulo 360, mapping the seam to +180 under positive policy or -180 otherwise.
When to use this tool
Use Geography: Longitude Seam Endpoint Policy when you need a longitude normalization, interval, or seam-policy calculation.
How to use the tool and how it works
- Enter longitudeDegrees, seamPolicy. 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 longitudeDegrees within ±one million and a positive or negative seam policy. Normalize modulo 360, mapping the seam to +180 under positive policy or -180 otherwise.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| longitudeDegrees | Longitude Degrees Unit: deg. | Required. Finite number. |
| seamPolicy | Seam Policy | Required. Text; one of "positive", "negative". 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.longitudeDegrees | Longitude Degrees | Calculated result member: number. |
{
"input": {
"longitudeDegrees": 180,
"seamPolicy": "negative"
},
"output": {
"result": {
"longitudeDegrees": -180
}
}
}Limitations and assumptions
- The output interval is (-180, 180] or [-180, 180) according to policy. Normalization does not change a coordinate reference system or locate a point by itself.
- 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 Arc Complement
Return the smaller of their absolute difference and its 360-degree complement as shortArcDegrees, and 360 minus that result as longArcDegrees.
- Longitude Cell Half Open Membership
Test membership in the west-inclusive, east-exclusive interval, using a union across the seam when west exceeds east.