--- a/progs/drumb.scala	Wed Nov 09 15:07:23 2016 +0000
+++ b/progs/drumb.scala	Thu Nov 10 00:15:14 2016 +0000
@@ -1,5 +1,5 @@
-// Advanvced Part 3 about Mr T. Drumb investing into stocks
-//==========================================================
+// Advanvced Part 3 about really dump investing strategy
+//=======================================================
 
 //two test portfolios
 
@@ -8,34 +8,55 @@
                             "DLR", "EQIX", "EQR", "ESS", "EXR", "FRT", "GGP", "HCP") 
 
 
-def get_yahoo_page(url: String): Option[List[String]] = ...
+// (1) The function below should obtain the first trading price
+// for a stock symbol by using the query
+//
+//    http://ichart.yahoo.com/table.csv?s=<<symbol>>&a=0&b=1&c=<<year>>&d=1&e=1&f=<<year>> 
+// 
+// and extracting the first January Adjusted Close price in a year.
 
 def get_first_price(symbol: String, year: Int): Option[Double] = ...
 
+// Complete the function below that obtains all first prices
+// for the stock symbols from a portfolio for the given
+// range of years
+
 def get_prices(portfolio: List[String], years: Range): List[List[Option[Double]]] = ...
 
+// test case
+//val p = get_prices(List("GOOG", "AAPL"), 2010 to 2012)
+
 
-//val p = get_prices(List("GOOG", "AAPL"), 2010 to 2012)
-
+// (2) The first function below calculates the change factor (delta) between
+// a price in year n and a price in year n+1. The second function calculates
+// all change factors for all prices (from a portfolio).
 
 def get_delta(price_old: Option[Double], price_new: Option[Double]): Option[Double] = ...
 
 def get_deltas(data: List[List[Option[Double]]]):  List[List[Option[Double]]] = ...
 
+// test case using the prices calculated above
 //val d = get_deltas(p)
 
 
+// (3) Write a function that given change factors, a starting balance and a year
+// calculates the yearly yield, i.e. new balanace, according to our dump investment 
+// strategy. Another function calculates given the same data calculates the
+// compound yield up to a given year. Finally a function combines all 
+// calculations by taking a portfolio, a range of years and a start balance
+// as arguments.
 
 def yearly_yield(data: List[List[Option[Double]]], balance: Long, year: Int): Long = ... 
 
+//test case
 //yearly_yield(d, 100, 0)
 
 def compound_yield(data: List[List[Option[Double]]], balance: Long, year: Int): Long = ... 
 
-
 def investment(portfolio: List[String], years: Range, start_balance: Long): Long = ...
 
 
+//test cases for the two portfolios given above
 //investment(rstate_portfolio, 1978 to 2016, 100)
 //investment(blchip_portfolio, 1978 to 2016, 100)