Reorganization

Makefile

@@ -1,13 +1,25 @@
-all: main tests
+# Makefile for Homework 6
+# by Mark <andrus@uchicago.edu>
 
-main: main.hs util.hs
-	# We must refer to iconv in /usr/lib
-	ghc -L/usr/lib main.hs -o main -fno-cse
+ghc = ghc
+flags = -O2
 
-tests: tests.hs util.hs
-	ghc -L/usr/lib -O2 tests.hs -o tests
+# NOTE: the following hack is a consequence of GHC for OS X being compiled against the libiconv in
+# `/usr/lib`
+extra_libs = -L/usr/lib
+
+bins = main tests
+deps = Utils.hs
+
+all: $(bins)
+
+main: Main.hs $(deps)
+	$(ghc) $(extra_libs) $(flags) $< -o $@
+
+tests: tests.hs $(deps)
+	$(ghc) $(extra_libs) $(flags) $< -o $@
 
 .PHONY: all clean
 
 clean:
-	rm -f *.hi *.o main tests
+	rm -f *.hi *.o $(bins)

util.hs → PowerMethod.hs

@@ -1,31 +1,16 @@
-{-# LANGUAGE FlexibleContexts #-}
+module PowerMethod (powerMethod) where
 
-module Util
-  ( isSymmetric
-  , powerMethod
-  ) where
-
-import Control.Monad
-import Data.List
 import Numeric.LinearAlgebra
 import System.Random
 import Debug.Trace
 
-isSymmetric :: (Element a, Eq a) => Matrix a -> Bool
-isSymmetric a = toLists a == toLists (trans a)
-
-vNormalize :: Vector Double -> Vector Double
-vNormalize v = recip (norm2 v) `scale` v
-
-mNormalize :: Matrix Double -> Matrix Double
-mNormalize m = recip (det m) `scale` m
+import Utils
 
 -- |powerIterations takes a seed for a random vector and an array, and returns a (hopefully)
 --  convergent list of `r` vectors zipped with their residuals using the power method; we want `r`
 --  to converge to the first eigenvector of the array
 powerIterations
   :: Int -> Matrix Double -> [(Vector Double, Double)]
-{-# NOINLINE powerIterations #-}
 powerIterations seed arr =
   -- NOTE: that `rows arr == cols arr`
   let r = (fromList . take (rows arr) $ repeat 1) `add` (randomVector seed Uniform $ rows arr)
@@ -46,6 +31,10 @@ powerIterations seed arr =
 --  to compute `lambda`), a precision parameter `epsilon`, a random seed for `powerIterations` and
 --  an array; NOTE: the array should already have eigenvectors 1 through `i` zeroed out
 eigVecAndVal :: Int -> Int -> Double -> Matrix Double -> (Vector Double, Double)
+-- NOTE: since we implement no checks as to whether the matrix passed in is actually decomposible,
+--       i.e., whether or not `r` will converge to the dominant eigenvector, `eigVecAndVal`
+--       occasionally stalls calling `powerIterations`--at which point it may be useful to
+--       uncomment the following line to enable visual inspection of the matrix
 {-eigVecAndVal seed i epsilon arr
   | trace ("eigVecAndVal " ++ show seed ++ " " ++ show i ++ " " ++ show epsilon ++ " " ++ show arr)
       False = undefined-}

Utils.hs

@@ -0,0 +1,18 @@
+{-# LANGUAGE FlexibleContexts #-}
+
+module Utils
+  ( isSymmetric
+  , vNormalize
+  , mNormalize
+  ) where
+
+import Numeric.LinearAlgebra
+
+isSymmetric :: (Element a, Eq a) => Matrix a -> Bool
+isSymmetric a = toLists a == toLists (trans a)
+
+vNormalize :: Vector Double -> Vector Double
+vNormalize v = recip (norm2 v) `scale` v
+
+mNormalize :: Matrix Double -> Matrix Double
+mNormalize m = recip (det m) `scale` m

main.hs

@@ -4,7 +4,8 @@ import Data.List
 import Numeric.LinearAlgebra
 import System.Random
 
-import Util
+import Utils
+import PowerMethod
 
 main :: IO ()
 main = do

tests.hs

@@ -9,7 +9,8 @@ import System.Random
 import Test.QuickCheck
 import Text.Printf
 
-import Util
+import Utils
+import PowerMethod
 
 compare :: (Eq a, Show a) => a -> a -> Property
 compare ans ref = printTestCase message (ref==ans)