add some comments for pd + some whitespaces1

1 files changed, 18 insertions, 12 deletions

diff --git a/AufgabeFFP1.hs b/AufgabeFFP1.hs
index 53e5fb7..f1c0e97 100644
--- a/AufgabeFFP1.hs
+++ b/AufgabeFFP1.hs
@@ -2,19 +2,10 @@ module AufgabeFFP1
 where
 
 -------------------------------------------------------------------------------
--- Helpers
-
--- !! Index function for Integer-type
-get ::  [a] -> Integer -> a
-get (x:xs) 0 = x
-get (x:xs) n = get xs (n-1)
-
-
--------------------------------------------------------------------------------
 
 -- recursive version
 pof2s :: [Integer]
-pof2s = 1:(map (2*) pof2s)
+pof2s = [1] ++ (map (2*) pof2s)
 
 -- alternate:
 -- calculates 2^ with each element of the continuous list
@@ -28,8 +19,18 @@ pof2s = 1:(map (2*) pof2s)
 -------------------------------------------------------------------------------
 
 -- recursive version:
+-- (1) [[1]]
+-- (2) zipWith (f) [[1]] [[1]]
+-- (2)   f(x=[1] y=[1])
+-- (2)     zipWith (+) ([0,1]) ([1,0]) = [1,1]
+-- (2)   = [[1,1]]
+-- (3) zipWith (f) [[1,1]] [[1,1]]
+-- (3)   f(x=[1,1] y=[1,1])
+-- (3)     zipWith (+) ([0,1,1]) ([1,1,0]) = [1,2,1]
+-- (3)   = [[1,2,1]]
+-- ...
 pd :: [[Integer]]
-pd = [1] : (zipWith (\x y -> zipWith (+) ([0]++x) (y++[0])) pd pd)
+pd = [[1]] ++ (zipWith (\x y -> zipWith (+) ([0] ++ x) (y ++ [0])) pd pd)
 
 -- alternate:
 -- pd :: [[Integer]]
@@ -57,10 +58,15 @@ pd = [1] : (zipWith (\x y -> zipWith (+) ([0]++x) (y++[0])) pd pd)
 fibdiag :: Integer -> [Integer]
 fibdiag n
   | n <= 0 = []
-  | otherwise = map (\x -> pd `get` (n-x) `get` (x-1)) [1..count]
+  | otherwise = map (\x -> pd `get` (n - x) `get` (x - 1)) [1..count]
   where
     count = (n + 1) `div` 2
 
+-- !! Index function for Integer-type
+get ::  [a] -> Integer -> a
+get (x:xs) 0 = x
+get (x:xs) n = get xs (n-1)
+
 -------------------------------------------------------------------------------
 
 fibdiags :: [[Integer]]