code: function ( t, p0, p1, p2, p3 ) {
  
  		return - 3 * p0 * ( 1 - t ) * ( 1 - t )  +
  			3 * p1 * ( 1 - t ) * ( 1 - t ) - 6 * t * p1 * ( 1 - t ) +
  			6 * t *  p2 * ( 1 - t ) - 3 * t * t * p2 +
  			3 * t * t * p3;
  
  	}
docs: Puay Bing, thanks for helping with this derivative!