I did this modification for a couple of reasons.
1) While using a modified Andrews' , I still feel that the (there are two one on top of the other) conform a little more closely with the commonly accepted rules of what are;
2) The have a little less steep upward slope which I believe conforms more to the reality of the price action;
3) While I think the drawn by ItisCalvin does a very good job reflecting the price , I believe - in the longer run - these will do an equal to better job while also potentially tipping us off to a price breakdown should the price drop below the lower .
As stated earlier, the used is a 50% . The 50% is used when the angle of the is overly steep. You can read how that is determined in Mikula's book. Normally a is drawn based on either athe high-low-high or the low-high-low price . In this instance, the is based on low-high-low - the low being $339.79. The 50% modification means instead of starting the at $339.79 you take the mid-way point between the first point $339.79 and the second point of $548. That gives $443.89 as the starting point of our modified .
After creating the first , it was cloned (copied) and placed on top of the original to give what you see in the chart. You'll notice that price have conformed quite nicely with the red median lines of each . Price recently bounced of the median-line of the lower which signals we may be in for a re-test of the mid-$550 or below as the lower is below $550.