Description
Normalize second minus first to [-180, 180) for signedDifferenceDegrees.
Bearings are circular coordinates, so zero and 360 degrees represent the same direction. Sector boundaries and true, magnetic, compass, or relative references need explicit conventions.
Normalize second minus first to [-180, 180) for signedDifferenceDegrees.
When to use this tool
Use Nautical Course Circular Difference when you need a bearing normalization, sign correction, or sector label.
How to use the tool and how it works
- Enter firstCourseDegrees, secondCourseDegrees. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read signedDifferenceDegrees. Use the output convention below.
Require courses in [0, 360). Normalize second minus first to [-180, 180) for signedDifferenceDegrees.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| firstCourseDegrees | First Course Degrees | Required. Finite number; minimum 0; strictly below 360. |
| secondCourseDegrees | Second Course Degrees | Required. Finite number; minimum 0; strictly below 360. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| signedDifferenceDegrees | Signed Difference Degrees | Required. Finite number. |
{
"input": {
"firstCourseDegrees": 350,
"secondCourseDegrees": 10
},
"output": {
"signedDifferenceDegrees": 20
}
}Limitations and assumptions
- The exact opposite-course tie is -180; inputs must share a reference and no route or collision interpretation is supplied.
- 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 current heading and magnetic information and a complete navigation process when interpreting an actual course or contact.
References
Similar or alternative tools
- Angle Phase Zero Reference
Reduce angleDegrees and zeroDegrees modulo 360 before subtracting, then normalize their difference into [0, 360).
- Polygon Turn Cross Product Sign
Form the cross product of the previous-to-current and current-to-next segments.