Description
Return west [-180, latitude] and east [180, latitude] as longitude-first pairs.
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.
Return west [-180, latitude] and east [180, latitude] as longitude-first pairs.
When to use this tool
Use Geographic Point Antimeridian Alias Pair when you need a longitude normalization, interval, or seam-policy calculation.
How to use the tool and how it works
- Enter latitude. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read west, east. Use the output convention below.
Require latitude within [-90, 90]. Return west [-180, latitude] and east [180, latitude] as longitude-first pairs.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| latitude | Latitude | Required. Finite number; minimum -90; maximum 90. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| west | West | Required. Array of finite number; maximum items 256. |
| east | East | Required. Array of finite number; maximum items 256. |
{
"input": {
"latitude": 45
},
"output": {
"west": [
-180,
45
],
"east": [
180,
45
]
}
}Limitations and assumptions
- Both pairs represent the same antimeridian direction with different longitude spellings. No full geometry, datum, bounding box, or seam-crossing route is constructed.
- 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
- Geography: Geographic Cell Angular Center
Compute the eastward wrapped longitude span, take its halfway point, and normalize into [-180, 180).
- Geography: Latitude Pole Reflection Step
Reflect a latitude beyond a pole once, add 180 degrees of longitude when reflected, and normalize longitude into [-180, 180).