    /**
     * @private
     */
    Ext.define('Ext.fx.CubicBezier', {

        /* Begin Definitions */

        singleton: true,

        /* End Definitions */

        cubicBezierAtTime: function(t, p1x, p1y, p2x, p2y, duration) {
            var cx = 3 * p1x,
                bx = 3 * (p2x - p1x) - cx,
                ax = 1 - cx - bx,
                cy = 3 * p1y,
                by = 3 * (p2y - p1y) - cy,
                ay = 1 - cy - by;
            function sampleCurveX(t) {
                return ((ax * t + bx) * t + cx) * t;
            }
            function solve(x, epsilon) {
                var t = solveCurveX(x, epsilon);
                return ((ay * t + by) * t + cy) * t;
            }
            function solveCurveX(x, epsilon) {
                var t0, t1, t2, x2, d2, i;
                for (t2 = x, i = 0; i < 8; i++) {
                    x2 = sampleCurveX(t2) - x;
                    if (Math.abs(x2) < epsilon) {
                        return t2;
                    }
                    d2 = (3 * ax * t2 + 2 * bx) * t2 + cx;
                    if (Math.abs(d2) < 1e-6) {
                        break;
                    }
                    t2 = t2 - x2 / d2;
                }
                t0 = 0;
                t1 = 1;
                t2 = x;
                if (t2 < t0) {
                    return t0;
                }
                if (t2 > t1) {
                    return t1;
                }
                while (t0 < t1) {
                    x2 = sampleCurveX(t2);
                    if (Math.abs(x2 - x) < epsilon) {
                        return t2;
                    }
                    if (x > x2) {
                        t0 = t2;
                    } else {
                        t1 = t2;
                    }
                    t2 = (t1 - t0) / 2 + t0;
                }
                return t2;
            }
            return solve(t, 1 / (200 * duration));
        },

        cubicBezier: function(x1, y1, x2, y2) {
            var fn = function(pos) {
                return Ext.fx.CubicBezier.cubicBezierAtTime(pos, x1, y1, x2, y2, 1);
            };
            fn.toCSS3 = function() {
                return 'cubic-bezier(' + [x1, y1, x2, y2].join(',') + ')';
            };
            fn.reverse = function() {
                return Ext.fx.CubicBezier.cubicBezier(1 - x2, 1 - y2, 1 - x1, 1 - y1);
            };
            return fn;
        }
    });