suvat/dst/index.js

A small TypeScript/JavaScript library for solving SUVAT equations.

export const formulas = Object.freeze({
    s: Object.freeze({
        u(d) { return d.v * d.t - 1 / 2 * d.a * d.t ** 2; },
        v(d) { return d.u * d.t + 1 / 2 * d.a * d.t ** 2; },
        a(d) { return d.t / 2 * (d.u + d.v); },
        t(d) { return (d.v ** 2 - d.u ** 2) / (2 * d.a); },
    }),
    u: Object.freeze({
        s(d) { return d.v - d.a * d.t; },
        v(d) { return (d.s - (1 / 2) * d.a * d.t ** 2) / d.t; },
        a(d) { return 2 * d.s / d.t - d.v; },
        t(d) { return (d.v ** 2 - 2 * d.a * d.s) ** (1 / 2); },
    }),
    v: Object.freeze({
        s(d) { return d.u + d.a * d.t; },
        u(d) { return (d.s + (1 / 2) * d.a * d.t ** 2) / d.t; },
        a(d) { return 2 * d.s / d.t - d.u; },
        t(d) { return (d.u ** 2 + 2 * d.a * d.s) ** (1 / 2); },
    }),
    a: Object.freeze({
        s(d) { return (d.v - d.u) / d.t; },
        u(d) { return 2 * (d.v * d.t - d.s) / (d.t ** 2); },
        v(d) { return 2 * (d.s - d.u * d.t) / (d.t ** 2); },
        t(d) { return (d.v ** 2 - d.u ** 2) / (2 * d.s); },
    }),
    t: Object.freeze({
        s(d) { return (d.v - d.u) / d.a; },
        u(d) { return (d.v - (d.v ** 2 - 2 * d.a * d.s) ** (1 / 2)) / d.a; },
        v(d) { return ((2 * d.a * d.s + d.u ** 2) ** (1 / 2) - d.u) / d.a; },
        a(d) { return (2 * d.s) / (d.u + d.v); },
    }),
});
export function complete(data) {
    // get unknowns
    const unknowns = [];
    for (const key of ["s", "u", "v", "a", "t"]) {
        if (!Number.isFinite(data[key]))
            unknowns.push(key);
    }
    // already complete
    if (unknowns.length === 0)
        return data;
    // too many unknowns
    if (unknowns.length > 2)
        return undefined;
    const out = { ...data };
    if (unknowns.length === 2) {
        // 2 unknowns
        out[unknowns[0]] = _stripFloat(formulas[unknowns[0]][unknowns[1]](data));
        out[unknowns[1]] = _stripFloat(formulas[unknowns[1]][unknowns[0]](data));
    }
    else {
        // 1 unknown
        out[unknowns[0]] = _stripFloat(Object.values(formulas[unknowns[0]])[0](data));
    }
    return out;
}
function _stripFloat(number) {
    return Math.round(number * 10000000000) / 10000000000;
}