Function fp64ify

docs/app/js/sanddance-app.js:68901–68909

(a)

parcelHelpers.export(exports, "fp64LowPart", ()=>fp64LowPart);
parcelHelpers.export(exports, "fp64ifyMatrix4", ()=>fp64ifyMatrix4);
function fp64ify(a) {
    var out = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : [];
    var startIndex = arguments.length > 2 && arguments[2] !== undefined ? arguments[2] : 0;
    var hiPart = Math.fround(a);
    var loPart = a - hiPart;
    out[startIndex] = hiPart;
    out[startIndex + 1] = loPart;
    return out;
}
function fp64LowPart(a) {
    return a - Math.fround(a);
}