Pole locations

Code snippets

curl "https://api.oanor.com/butterworth-api/v1/poles" \
  -H "x-oanor-key: oanor_test_..."

await fetch("https://api.oanor.com/butterworth-api/v1/poles", {
  headers: { "x-oanor-key": "oanor_test_..." }
});

$ch = curl_init("https://api.oanor.com/butterworth-api/v1/poles");
curl_setopt($ch, CURLOPT_HTTPHEADER, ["x-oanor-key: oanor_test_..."]);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$out = curl_exec($ch);

import requests
requests.get(
    "https://api.oanor.com/butterworth-api/v1/poles",
    headers={"x-oanor-key": "oanor_test_..."}
)

Example response

A real response from this endpoint, captured by the latest health check.

{
    "data": {
        "note": "Butterworth poles lie equally spaced on a circle of radius ωc in the left half of the s-plane, at angles π·(2k+n−1)/(2n). They are all stable (negative real part).",
        "poles": [
            {
                "imag": 0.92387953,
                "real": -0.38268343,
                "angle_deg": 112.5
            },
            {
                "imag": 0.38268343,
                "real": -0.92387953,
                "angle_deg": 157.5
            },
            {
                "imag": -0.38268343,
                "real": -0.92387953,
                "angle_deg": 202.5
            },
            {
                "imag": -0.92387953,
                "real": -0.38268343,
                "angle_deg": 247.5
            }
        ],
        "inputs": {
            "order": 4,
            "cutoff": 1
        }
    },
    "meta": {
        "timestamp": "2026-06-05T11:30:23.019Z",
        "request_id": "f878f0e9-5fe0-4ce5-bc85-2747919f173a"
    },
    "status": "ok",
    "message": "Pole locations",
    "success": true
}