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|
{-# LANGUAGE ViewPatterns #-}
module Math.LinProg.LPSolve (
solve
,ResultCode(..)
) where
import Control.Applicative
import Control.Monad
import Data.List
import Control.Lens
import Math.LinProg.LPSolve.FFI hiding (solve)
import qualified Math.LinProg.LPSolve.FFI as F
import Math.LinProg.LP
import Math.LinProg.Types
import qualified Data.Map as M
import Prelude hiding (EQ)
solve :: (Eq v, Ord v) => LinProg Double v () -> IO (Either (Maybe ResultCode) [(v, Double)])
solve (compile -> lp) = do
model <- makeLP nconstr nvars
case model of
Nothing -> return (Left Nothing)
Just m' -> with m' $ \m -> do
-- Eqs
forM_ (zip [1..] $ lp ^. equals) $ \(i, eq) ->
forM_ (M.keys varLUT) $ \v -> do
let w = getVar v $ fst eq
c = negate $ snd eq
when (w /= 0) $ do
setMat m i (varLUT M.! v) w
setConstrType m i EQ
setRHS m i c
return ()
-- Leqs
forM_ (zip [1+nequals..] $ lp ^. leqs) $ \(i, eq) ->
forM_ (M.keys varLUT) $ \v -> do
let w = getVar v $ fst eq
c = negate $ snd eq
when (w /= 0) $ do
setMat m i (varLUT M.! v) w
setConstrType m i LE
setRHS m i c
return ()
-- Objective
forM_ (M.keys varLUT) $ \v -> do
let w = getVar v $ lp ^. objective
when (w /= 0) $ void $ setMat m 0 (varLUT M.! v) w
res <- F.solve m
case res of
Optimal -> do
sol <- snd <$> getSol nvars m
return $ Right (zip (M.keys varLUT) sol)
_ -> return $ Left (Just res)
where
nconstr = length allConstr
nvars = M.size varLUT
nequals = length (lp ^. equals)
allConstr = (lp ^. equals) ++ (lp ^. leqs)
varLUT = M.fromList $ zip (sort $ nub $ concatMap (vars . fst) allConstr) [1..]
with m f = do
r <- f m
freeLP m
return r
|
