3D Arrows

from dataviz import quiver3d, save

def main() raises:
    # Illustrative circulation: a field turning about the z axis
    # and drifting upward as it goes.
    var x = List[Float64]()
    var y = List[Float64]()
    var z = List[Float64]()
    var u = List[Float64]()
    var v = List[Float64]()
    var w = List[Float64]()
    for k in range(3):
        for j in range(3):
            for i in range(3):
                var px = Float64(i) - 1.0
                var py = Float64(j) - 1.0
                var pz = Float64(k) - 1.0
                x.append(px)
                y.append(py)
                z.append(pz)
                u.append(-py * 0.35)
                v.append(px * 0.35)
                w.append(0.25)

    var c = quiver3d(
        x, y, z, u, v, w, title="Illustrative Circulating Field"
    )
    save(c, "docs/src/examples/out_quiver3d.svg")