pi, π (constant)

{
    "$id": "https://schemas.optimade.org/defs/v1.2/constants/math/basic/pi",
    "$schema": "https://schemas.optimade.org/meta/v1.2/optimade/constant_definition.json",
    "title": "pi",
    "symbol": "pi",
    "display-symbol": "\u03c0",
    "description": "The ratio of a circle's circumference to its diameter. Approximately equal to 3.1415926.\n\nAn early definition of \u03c0 as the symbol for the ratio of a circle's circumference to its diameter goes back to William Jones, Synopsis Palmariorum Matheseos (1706), page 263.",
    "resources": [
        {
            "relation": "Definition in William Jones, Synopsis Palmariorum Matheseos (1706)",
            "resource-id": "https://archive.org/details/SynopsisPalmariorumMatheseosOrANewIntroductionToTheMathematics/page/n283/"
        },
        {
            "relation": "Wikipedia article describing the constant",
            "resource-id": "https://en.wikipedia.org/wiki/Pi"
        }
    ],
    "approximate-relations": [
        {
            "scale": {
                "value": 3.141592653589793
            }
        }
    ],
    "x-optimade-definition": {
        "label": "pi_constant_math_basic",
        "kind": "constant",
        "format": "1.2",
        "version": "1.2.0",
        "name": "pi"
    }
}