zyntax/crates/zynml/examples/bench_nbody_ref.zynml at main · zyntax-project/zyntax · GitHub

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import prelude

// N-body bench — exact port of rayzor's
// `compiler/benchmarks/haxe/BMNBodyCode.hx`, which itself is the
// HaxeBenchmarks reference n-body. The reference does 20 × 500_000
// = 10_000_000 calls to `advance(0.01)` and returns the system's
// energy × 1_000_000 truncated to `int`.
//
// Algorithm parity is what makes this comparable to rayzor:
//   * Newtonian gravity with `mag = dt / r³` (rayzor uses
//     `Math.sqrt(d²) * d² = r³`, identical via the
//     `r³ = r · r²` reformulation).
//   * Five bodies with the standard `Sun + four outer planets`
//     initial conditions, momentum-balanced via offsetMomentum.
//   * `0.5 * 1e-6 * (v² · m - Σ pair-potential)` as the energy
//     calculation, scaled by 1_000_000 and truncated.
//
// ZynML difference today: prelude's `sqrt` is a 12-iteration
// Newton-Raphson rather than a hardware FSQRT, so a meaningful
// chunk of the bench time is in `prelude::sqrt`. Wiring
// `Intrinsic::Sqrt` from the Cranelift backend (already plumbed)
// to the ZynML `sqrt` name is the natural follow-up — call sites
// don't change.

@reference
struct Body {
    x: f64,
    y: f64,
    z: f64,
    vx: f64,
    vy: f64,
    vz: f64,
    mass: f64
}

def advance(bodies: Array<Body>, n: i64, dt: f64): i64 {
    let mut i: i64 = 0
    while i < n {
        let mut a = bodies[i]
        let mut j: i64 = i + 1
        while j < n {
            let mut b = bodies[j]
            let dx = a.x - b.x
            let dy = a.y - b.y
            let dz = a.z - b.z
            let d2 = dx * dx + dy * dy + dz * dz
            let distance = sqrt(d2)
            let mag = dt / (distance * distance * distance)

            a.vx = a.vx - dx * b.mass * mag
            a.vy = a.vy - dy * b.mass * mag
            a.vz = a.vz - dz * b.mass * mag

            b.vx = b.vx + dx * a.mass * mag
            b.vy = b.vy + dy * a.mass * mag
            b.vz = b.vz + dz * a.mass * mag

            bodies[j] = b
            j = j + 1
        }
        bodies[i] = a
        i = i + 1
    }

    let mut k: i64 = 0
    while k < n {
        let mut body = bodies[k]
        body.x = body.x + dt * body.vx
        body.y = body.y + dt * body.vy
        body.z = body.z + dt * body.vz
        bodies[k] = body
        k = k + 1
    }
    return n
}

def energy(bodies: Array<Body>, n: i64): f64 {
    let mut e: f64 = 0.0
    let mut i: i64 = 0
    while i < n {
        let a = bodies[i]
        e = e + 0.5 * a.mass * (a.vx * a.vx + a.vy * a.vy + a.vz * a.vz)
        let mut j: i64 = i + 1
        while j < n {
            let b = bodies[j]
            let dx = b.x - a.x
            let dy = b.y - a.y
            let dz = b.z - a.z
            let d2 = dx * dx + dy * dy + dz * dz
            e = e - (a.mass * b.mass) / sqrt(d2)
            j = j + 1
        }
        i = i + 1
    }
    return e
}

def main(): i64 {
    let solar_mass: f64 = 39.478417604357434
    let days_per_year: f64 = 365.24

    let sun = Body {
        x: 0.0, y: 0.0, z: 0.0,
        vx: 0.0, vy: 0.0, vz: 0.0,
        mass: solar_mass
    }
    let jupiter = Body {
        x: 4.84143144246472,
        y: -1.16032004402742,
        z: -0.103622044471123,
        vx: 0.00166007664274403 * days_per_year,
        vy: 0.00769901118419740 * days_per_year,
        vz: -0.0000690460016972 * days_per_year,
        mass: 0.000954791938424 * solar_mass
    }
    let saturn = Body {
        x: 8.34336671824458,
        y: 4.12479856412430,
        z: -0.403523417114321,
        vx: -0.00276742510726862 * days_per_year,
        vy: 0.00499852801234917 * days_per_year,
        vz: 0.0000230417297573 * days_per_year,
        mass: 0.000285885980666 * solar_mass
    }
    let uranus = Body {
        x: 12.8943695621391,
        y: -15.1111514016986,
        z: -0.223307578892655,
        vx: 0.00296460137564761 * days_per_year,
        vy: 0.00237847173959480 * days_per_year,
        vz: -0.0000296589568540 * days_per_year,
        mass: 0.0000436624404335 * solar_mass
    }
    let neptune = Body {
        x: 15.3796971148509,
        y: -25.9193146099879,
        z: 0.179258772950371,
        vx: 0.00268067772490389 * days_per_year,
        vy: 0.00162824170038242 * days_per_year,
        vz: -0.0000951592254519 * days_per_year,
        mass: 0.0000515138902046 * solar_mass
    }

    let bodies = [sun, jupiter, saturn, uranus, neptune]
    let n: i64 = 5

    // Offset the Sun's momentum so the system's centre of mass is
    // stationary — without this the long-running integration error
    // explodes as the COM drifts.
    let mut px: f64 = 0.0
    let mut py: f64 = 0.0
    let mut pz: f64 = 0.0
    let mut i: i64 = 0
    while i < n {
        let b = bodies[i]
        px = px + b.vx * b.mass
        py = py + b.vy * b.mass
        pz = pz + b.vz * b.mass
        i = i + 1
    }
    let mut s = bodies[0]
    s.vx = 0.0 - px / solar_mass
    s.vy = 0.0 - py / solar_mass
    s.vz = 0.0 - pz / solar_mass
    bodies[0] = s

    let dt: f64 = 0.01
    // 20 × 500_000 = 10_000_000 advance calls, matching rayzor's
    // HaxeBenchmarks shape exactly.
    let mut outer: i64 = 0
    while outer < 20 {
        let mut step: i64 = 0
        while step < 500000 {
            advance(bodies, n, dt)
            step = step + 1
        }
        outer = outer + 1
    }

    // Return Std.int(energy * 1_000_000) — rayzor's checksum form.
    let e: f64 = energy(bodies, n)
    return (e * 1000000.0) as i64
}