var tween = {   
    linear: function(t,b,c,d){ return c*t/d + b; },   
    quad: {   
        easein: function(t,b,c,d){   
            return c*(t/=d)*t + b;   
        },   
        easeout: function(t,b,c,d){   
            return -c *(t/=d)*(t-2) + b;   
        },   
        easeinout: function(t,b,c,d){   
            if ((t/=d/2) < 1) return c/2*t*t + b;   
            return -c/2 * ((--t)*(t-2) - 1) + b;   
        }   
    },   
    cubic: {   
        easein: function(t,b,c,d){   
            return c*(t/=d)*t*t + b;   
        },   
        easeout: function(t,b,c,d){   
            return c*((t=t/d-1)*t*t + 1) + b;   
        },   
        easeinout: function(t,b,c,d){   
            if ((t/=d/2) < 1) return c/2*t*t*t + b;   
            return c/2*((t-=2)*t*t + 2) + b;   
        }   
    },   
    quart: {   
        easein: function(t,b,c,d){   
            return c*(t/=d)*t*t*t + b;   
        },   
        easeout: function(t,b,c,d){   
            return -c * ((t=t/d-1)*t*t*t - 1) + b;   
        },   
        easeinout: function(t,b,c,d){   
            if ((t/=d/2) < 1) return c/2*t*t*t*t + b;   
            return -c/2 * ((t-=2)*t*t*t - 2) + b;   
        }   
    },   
    quint: {   
        easein: function(t,b,c,d){   
            return c*(t/=d)*t*t*t*t + b;   
        },   
        easeout: function(t,b,c,d){   
            return c*((t=t/d-1)*t*t*t*t + 1) + b;   
        },   
        easeinout: function(t,b,c,d){   
            if ((t/=d/2) < 1) return c/2*t*t*t*t*t + b;   
            return c/2*((t-=2)*t*t*t*t + 2) + b;   
        }   
    },   
    sine: {   
        easein: function(t,b,c,d){   
            return -c * math.cos(t/d * (math.pi/2)) + c + b;   
        },   
        easeout: function(t,b,c,d){   
            return c * math.sin(t/d * (math.pi/2)) + b;   
        },   
        easeinout: function(t,b,c,d){   
            return -c/2 * (math.cos(math.pi*t/d) - 1) + b;   
        }   
    },   
    expo: {   
        easein: function(t,b,c,d){   
            return (t==0) ? b : c * math.pow(2, 10 * (t/d - 1)) + b;   
        },   
        easeout: function(t,b,c,d){   
            return (t==d) ? b+c : c * (-math.pow(2, -10 * t/d) + 1) + b;   
        },   
        easeinout: function(t,b,c,d){   
            if (t==0) return b;   
            if (t==d) return b+c;   
            if ((t/=d/2) < 1) return c/2 * math.pow(2, 10 * (t - 1)) + b;   
            return c/2 * (-math.pow(2, -10 * --t) + 2) + b;   
        }   
    },   
    circ: {   
        easein: function(t,b,c,d){   
            return -c * (math.sqrt(1 - (t/=d)*t) - 1) + b;   
        },   
        easeout: function(t,b,c,d){   
            return c * math.sqrt(1 - (t=t/d-1)*t) + b;   
        },   
        easeinout: function(t,b,c,d){   
            if ((t/=d/2) < 1) return -c/2 * (math.sqrt(1 - t*t) - 1) + b;   
            return c/2 * (math.sqrt(1 - (t-=2)*t) + 1) + b;   
        }   
    },   
    elastic: {   
        easein: function(t,b,c,d,a,p){   
            if (t==0) return b;  if ((t/=d)==1) return b+c;  if (!p) p=d*.3;   
            if (!a || a < math.abs(c)) { a=c; var s=p/4; }   
            else var s = p/(2*math.pi) * math.asin (c/a);   
            return -(a*math.pow(2,10*(t-=1)) * math.sin( (t*d-s)*(2*math.pi)/p )) + b;   
        },   
        easeout: function(t,b,c,d,a,p){   
            if (t==0) return b;  if ((t/=d)==1) return b+c;  if (!p) p=d*.3;   
            if (!a || a < math.abs(c)) { a=c; var s=p/4; }   
            else var s = p/(2*math.pi) * math.asin (c/a);   
            return (a*math.pow(2,-10*t) * math.sin( (t*d-s)*(2*math.pi)/p ) + c + b);   
        },   
        easeinout: function(t,b,c,d,a,p){   
            if (t==0) return b;  if ((t/=d/2)==2) return b+c;  if (!p) p=d*(.3*1.5);   
            if (!a || a < math.abs(c)) { a=c; var s=p/4; }   
            else var s = p/(2*math.pi) * math.asin (c/a);   
            if (t < 1) return -.5*(a*math.pow(2,10*(t-=1)) * math.sin( (t*d-s)*(2*math.pi)/p )) + b;   
            return a*math.pow(2,-10*(t-=1)) * math.sin( (t*d-s)*(2*math.pi)/p )*.5 + c + b;   
        }   
    },   
    back: {   
        easein: function(t,b,c,d,s){   
            if (s == undefined) s = 1.70158;   
            return c*(t/=d)*t*((s+1)*t - s) + b;   
        },   
        easeout: function(t,b,c,d,s){   
            if (s == undefined) s = 1.70158;   
            return c*((t=t/d-1)*t*((s+1)*t + s) + 1) + b;   
        },   
        easeinout: function(t,b,c,d,s){   
            if (s == undefined) s = 1.70158;    
            if ((t/=d/2) < 1) return c/2*(t*t*(((s*=(1.525))+1)*t - s)) + b;   
            return c/2*((t-=2)*t*(((s*=(1.525))+1)*t + s) + 2) + b;   
        }   
    },   
    bounce: {   
        easein: function(t,b,c,d){   
            return c - tween.bounce.easeout(d-t, 0, c, d) + b;   
        },   
        easeout: function(t,b,c,d){   
            if ((t/=d) < (1/2.75)) {   
                return c*(7.5625*t*t) + b;   
            } else if (t < (2/2.75)) {   
                return c*(7.5625*(t-=(1.5/2.75))*t + .75) + b;   
            } else if (t < (2.5/2.75)) {   
                return c*(7.5625*(t-=(2.25/2.75))*t + .9375) + b;   
            } else {   
                return c*(7.5625*(t-=(2.625/2.75))*t + .984375) + b;   
            }   
        },   
        easeinout: function(t,b,c,d){   
            if (t < d/2) return tween.bounce.easein(t*2, 0, c, d) * .5 + b;   
            else return tween.bounce.easeout(t*2-d, 0, c, d) * .5 + c*.5 + b;   
        }   
    }   
}