Safe Haskell  None 

Language  Haskell98 
Usage:
 create an optimization problem of type
Config
by one ofminimize
,minimizeIO
etc. run
it.
Let's optimize the following function f(xs). xs
is a list of
Double and f
has its minimum at xs !! i = sqrt(i)
.
>>>
import Test.DocTest.Prop
>>>
let f = sum . zipWith (\i x > (x*abs x  i)**2) [0..] :: [Double] > Double
>>>
let initXs = replicate 10 0 :: [Double]
>>>
bestXs < run $ minimize f initXs
>>>
assert $ f bestXs < 1e10
If your optimization is not working well, try:
 Set
scaling
in theConfig
to the appropriate search range of each parameter.  Set
tolFun
in theConfig
to the appropriate scale of the function values.
An example for scaling the function value:
>>>
let f2 xs = (/1e100) $ sum $ zipWith (\i x > (x*abs x  i)**2) [0..] xs
>>>
bestXs < run $ (minimize f2 $ replicate 10 0) {tolFun = Just 1e111}
>>>
assert $ f2 bestXs < 1e110
An example for scaling the input values:
>>>
let f3 xs = sum $ zipWith (\i x > (x*abs x  i)**2) [0,1e100..] xs
>>>
let xs30 = replicate 10 0 :: [Double]
>>>
let m3 = (minimize f3 xs30) {scaling = Just (repeat 1e50)}
>>>
xs31 < run $ m3
>>>
assert $ f3 xs31 / f3 xs30 < 1e10
Use minimizeT
to optimize functions on traversable structures.
>>>
import qualified Data.Vector as V
>>>
let f4 = V.sum . V.imap (\i x > (x*abs x  fromIntegral i)**2)
>>>
:t f4
f4 :: V.Vector Double > Double>>>
bestVx < run $ minimizeT f4 $ V.replicate 10 0
>>>
assert $ f4 bestVx < 1e10
Or use minimizeG
to optimize functions of any type that is Data
and that contains Double
s. Here is an example that deal with
Triangles.
>>>
:set XDeriveDataTypeable
>>>
import Data.Data
>>>
data Pt = Pt Double Double deriving (Typeable,Data)
>>>
let dist (Pt ax ay) (Pt bx by) = ((axbx)**2 + (ayby)**2)**0.5
>>>
data Triangle = Triangle Pt Pt Pt deriving (Typeable,Data)
Let us create a triangle ABC so that AB = 3, AC = 4, BC = 5.
>>>
let f5 (Triangle a b c) = (dist a b  3.0)**2 + (dist a c  4.0)**2 + (dist b c  5.0)**2
>>>
let triangle0 = Triangle o o o where o = Pt 0 0
>>>
:t f5
f5 :: Triangle > Double>>>
bestTriangle < run $ (minimizeG f5 triangle0){tolFun = Just 1e20}
>>>
assert $ f5 bestTriangle < 1e10
Then the angle BAC should be orthogonal.
>>>
let (Triangle (Pt ax ay) (Pt bx by) (Pt cx cy)) = bestTriangle
>>>
assert $ abs ((bxax)*(cxax) + (byay)*(cyay)) < 1e10
When optimizing noisy functions, set noiseHandling
= True
(and
increase noiseReEvals
) for better results.
>>>
import System.Random
>>>
let noise = randomRIO (0,1e2)
>>>
let f6Pure = sum . zipWith (\i x > (x*abs x  i)**2) [0..]
>>>
let f6 xs = fmap (f6Pure xs +) noise
>>>
:t f6
f6 :: [Double] > IO Double>>>
xs60 < run $ (minimizeIO f6 $ replicate 10 0) {noiseHandling = False}
>>>
xs61 < run $ (minimizeIO f6 $ replicate 10 0) {noiseHandling = True,noiseReEvals=Just 10}
>>>
 assert $ f6Pure xs61 < f6Pure xs60
(note : the above assertion holds with probability of about 70%.)
 run :: forall tgt. Config tgt > IO tgt
 data Config tgt = Config {
 funcIO :: tgt > IO Double
 projection :: tgt > [Double]
 embedding :: [Double] > tgt
 initXs :: [Double]
 sigma0 :: Double
 scaling :: Maybe [Double]
 typicalXs :: Maybe [Double]
 noiseHandling :: Bool
 noiseReEvals :: Maybe Int
 noiseEps :: Maybe Double
 tolFacUpX :: Maybe Double
 tolUpSigma :: Maybe Double
 tolFun :: Maybe Double
 tolStagnation :: Maybe Int
 tolX :: Maybe Double
 verbose :: Bool
 otherArgs :: [(String, String)]
 pythonPath :: Maybe FilePath
 cmaesWrapperPath :: Maybe FilePath
 defaultConfig :: Config a
 minimize :: ([Double] > Double) > [Double] > Config [Double]
 minimizeIO :: ([Double] > IO Double) > [Double] > Config [Double]
 minimizeT :: Traversable t => (t Double > Double) > t Double > Config (t Double)
 minimizeTIO :: Traversable t => (t Double > IO Double) > t Double > Config (t Double)
 minimizeG :: Data a => (a > Double) > a > Config a
 minimizeGIO :: Data a => (a > IO Double) > a > Config a
 getDoubles :: Data a => a > [Double]
 putDoubles :: Data a => [Double] > a > a
Documentation
Optimizer configuration. tgt
is the type of the value to be
optimized.
Config  

defaultConfig :: Config a Source
The default Config
values. Also consult the original document
http://www.lri.fr/~hansen/pythoncma.html#fmin for default values
of the parameters not listed here.
minimize :: ([Double] > Double) > [Double] > Config [Double] Source
Create a minimizing problem, given a pure function and an initial guess.
minimizeIO :: ([Double] > IO Double) > [Double] > Config [Double] Source
Create a minimizing problem, given an IO
function and an initial guess.
minimizeT :: Traversable t => (t Double > Double) > t Double > Config (t Double) Source
Create a minimizing problem for a function on traversable structure t
.
minimizeTIO :: Traversable t => (t Double > IO Double) > t Double > Config (t Double) Source
Create a minimizing problem for an effectful function on a traversable structure t
.
minimizeG :: Data a => (a > Double) > a > Config a Source
Create a minimizing problem for a function on almost any type a
which contain Doubles.
minimizeGIO :: Data a => (a > IO Double) > a > Config a Source
Create a minimizing problem for an effectful function of almost any type.
getDoubles :: Data a => a > [Double] Source
getDoubles and putDoubles are generic functions used to put [Double] in and out of generic data types. Let's test them.
>>>
let d3 = (1,2,3) :: (Double,Int,Double)
>>>
getDoubles d3
[1.0,3.0]>>>
putDoubles [4,5] d3
(4.0,2,5.0)
>>>
let complicated = ([0,1],(2,[3,4])) :: ([Double],(Double,[Double]))
>>>
getDoubles complicated
[0.0,1.0,2.0,3.0,4.0]>>>
putDoubles [5,6,7,8,9] complicated
([5.0,6.0],(7.0,[8.0,9.0]))
Putting back the obtained values should not change the data.
>>>
import Test.DocTest.Prop
>>>
type Complicated = ([[Double]],(),(([(Double,String)]),[Double]))
>>>
prop ((\x > putDoubles (getDoubles x) x == x) :: Complicated > Bool)
You can get the original list back after putting it.
>>>
let make3 xs = take 3 $ xs ++ [0..]
>>>
prop ((\xs' y > let xs = make3 xs' in getDoubles (putDoubles xs y)==xs) :: [Double] > (Double,Double,Double) > Bool)
putDoubles :: Data a => [Double] > a > a Source