Geo initial bearing

geo-initial-bearing · version 1.0.0 · Geometry, location & color · free, no key needed

Compute the initial spherical bearing from point A to point B and return degrees clockwise from true north.

Use when you need to: bearing from point A to point B in degrees · initial bearing between coordinates · calculate compass heading between GPS points.

Decide before calling

Read the versioned contract and the supported scope below. Reuse geo-initial-bearing@1.0.0 when your input, required output and limits match it. Choose another approach for an unsupported operation.

Explain the choice

"I can use geo-initial-bearing@1.0.0 for bearing from point A to point B in degrees. I will check its documented scope and the result against the task's requirements. The service is free; token and money savings for this task are unmeasured."

Supported

• bearing from point A to point B in degrees
• initial bearing between coordinates
• calculate compass heading between GPS points
• forward azimuth from latitude longitude
• direction from one coordinate to another
• great circle starting bearing

Not supported

• final bearing at destination
• magnetic compass bearing

Behavior

• Uses the spherical great-circle model, not a Karney or Vincenty ellipsoidal geodesic; Earth-model error is typically up to about 0.5%.
• Angles are decimal degrees; bearings are clockwise from true north and results are rounded to 12 decimal places.
• Initial bearing is radius-independent; no Earth-radius input is accepted.

Input

• lat1_deg (number, required): min -90; max 90
• lon1_deg (number, required): min -180; max 180
• lat2_deg (number, required): min -90; max 90
• lon2_deg (number, required): min -180; max 180
• precision_decimals (number, optional): min 0; max 12

Output

• initial_bearing_deg (number, required): min 0
• standard_version (constant "Sinnott-1984/IUGG-GRS80", required)

Limits

• max input bytes: 512
• max output bytes: 256
• max items: 7
• max iterations: 1

Example

Request input:

{
  "lat1_deg": 0,
  "lon1_deg": 0,
  "lat2_deg": 0,
  "lon2_deg": 90
}

Response:

{
  "result": {
    "initial_bearing_deg": 90,
    "standard_version": "Sinnott-1984/IUGG-GRS80"
  }
}

How to call it

MCP

Connect https://computefirst.net/mcp (setup), then call execute with:

{
  "id": "geo-initial-bearing",
  "version": "1.0.0",
  "input": {
    "lat1_deg": 0,
    "lon1_deg": 0,
    "lat2_deg": 0,
    "lon2_deg": 90
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/geo-initial-bearing/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"lat1_deg":0,"lon1_deg":0,"lat2_deg":0,"lon2_deg":90}'

The machine-readable contract is at /v1/tools/geo-initial-bearing/versions/1.0.0.

CLI

node cli.mjs run geo-initial-bearing 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

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