{-# LANGUAGE TypeOperators #-}
{-# LANGUAGE ViewPatterns #-}

-----------------------------------------------------------------------------
-- |
-- Module      :  Numeric.LinearAlgebra.LAPACK
-- Copyright   :  (c) Alberto Ruiz 2006-14
-- License     :  BSD3
-- Maintainer  :  Alberto Ruiz
-- Stability   :  provisional
--
-- Functional interface to selected LAPACK functions (<http://www.netlib.org/lapack>).
--
-----------------------------------------------------------------------------


module Internal.LAPACK where

import Internal.Devel
import Internal.Vector
import Internal.Matrix hiding ((#))
import Internal.Conversion
import Internal.Element
import Foreign.Ptr(nullPtr)
import Foreign.C.Types
import Control.Monad(when)
import System.IO.Unsafe(unsafePerformIO)

-----------------------------------------------------------------------------------

infixl 1 #
a # b = apply a b
{-# INLINE (#) #-}

-----------------------------------------------------------------------------------

type TMMM t = t ::> t ::> t ::> Ok

type F = Float
type Q = Complex Float

foreign import ccall unsafe "multiplyR" dgemmc :: CInt -> CInt -> TMMM R
foreign import ccall unsafe "multiplyC" zgemmc :: CInt -> CInt -> TMMM C
foreign import ccall unsafe "multiplyF" sgemmc :: CInt -> CInt -> TMMM F
foreign import ccall unsafe "multiplyQ" cgemmc :: CInt -> CInt -> TMMM Q
foreign import ccall unsafe "multiplyI" c_multiplyI :: I -> TMMM I
foreign import ccall unsafe "multiplyL" c_multiplyL :: Z -> TMMM Z

isT (rowOrder -> False) = 0
isT _                   = 1

tt x@(rowOrder -> False) = x
tt x                     = trans x

multiplyAux f st a b = unsafePerformIO $ do
    when (cols a /= rows b) $ error $ "inconsistent dimensions in matrix product "++
                                       show (rows a,cols a) ++ " x " ++ show (rows b, cols b)
    s <- createMatrix ColumnMajor (rows a) (cols b)
    f (isT a) (isT b) # (tt a) # (tt b) # s #| st
    return s

-- | Matrix product based on BLAS's /dgemm/.
multiplyR :: Matrix Double -> Matrix Double -> Matrix Double
multiplyR a b = {-# SCC "multiplyR" #-} multiplyAux dgemmc "dgemmc" a b

-- | Matrix product based on BLAS's /zgemm/.
multiplyC :: Matrix (Complex Double) -> Matrix (Complex Double) -> Matrix (Complex Double)
multiplyC a b = multiplyAux zgemmc "zgemmc" a b

-- | Matrix product based on BLAS's /sgemm/.
multiplyF :: Matrix Float -> Matrix Float -> Matrix Float
multiplyF a b = multiplyAux sgemmc "sgemmc" a b

-- | Matrix product based on BLAS's /cgemm/.
multiplyQ :: Matrix (Complex Float) -> Matrix (Complex Float) -> Matrix (Complex Float)
multiplyQ a b = multiplyAux cgemmc "cgemmc" a b

multiplyI :: I -> Matrix CInt -> Matrix CInt -> Matrix CInt
multiplyI m a b = unsafePerformIO $ do
    when (cols a /= rows b) $ error $
        "inconsistent dimensions in matrix product "++ shSize a ++ " x " ++ shSize b
    s <- createMatrix ColumnMajor (rows a) (cols b)
    c_multiplyI m # a # b # s #|"c_multiplyI"
    return s

multiplyL :: Z -> Matrix Z -> Matrix Z -> Matrix Z
multiplyL m a b = unsafePerformIO $ do
    when (cols a /= rows b) $ error $
        "inconsistent dimensions in matrix product "++ shSize a ++ " x " ++ shSize b
    s <- createMatrix ColumnMajor (rows a) (cols b)
    c_multiplyL m # a # b # s #|"c_multiplyL"
    return s

-----------------------------------------------------------------------------

type TSVD t = t ::> t ::> R :> t ::> Ok

foreign import ccall unsafe "svd_l_R" dgesvd :: TSVD R
foreign import ccall unsafe "svd_l_C" zgesvd :: TSVD C
foreign import ccall unsafe "svd_l_Rdd" dgesdd :: TSVD R
foreign import ccall unsafe "svd_l_Cdd" zgesdd :: TSVD C

-- | Full SVD of a real matrix using LAPACK's /dgesvd/.
svdR :: Matrix Double -> (Matrix Double, Vector Double, Matrix Double)
svdR = svdAux dgesvd "svdR"

-- | Full SVD of a real matrix using LAPACK's /dgesdd/.
svdRd :: Matrix Double -> (Matrix Double, Vector Double, Matrix Double)
svdRd = svdAux dgesdd "svdRdd"

-- | Full SVD of a complex matrix using LAPACK's /zgesvd/.
svdC :: Matrix (Complex Double) -> (Matrix (Complex Double), Vector Double, Matrix (Complex Double))
svdC = svdAux zgesvd "svdC"

-- | Full SVD of a complex matrix using LAPACK's /zgesdd/.
svdCd :: Matrix (Complex Double) -> (Matrix (Complex Double), Vector Double, Matrix (Complex Double))
svdCd = svdAux zgesdd "svdCdd"

svdAux f st x = unsafePerformIO $ do
    a <- copy ColumnMajor x
    u <- createMatrix ColumnMajor r r
    s <- createVector (min r c)
    v <- createMatrix ColumnMajor c c
    f # a # u # s # v #| st
    return (u,s,v)
  where
    r = rows x
    c = cols x


-- | Thin SVD of a real matrix, using LAPACK's /dgesvd/ with jobu == jobvt == \'S\'.
thinSVDR :: Matrix Double -> (Matrix Double, Vector Double, Matrix Double)
thinSVDR = thinSVDAux dgesvd "thinSVDR"

-- | Thin SVD of a complex matrix, using LAPACK's /zgesvd/ with jobu == jobvt == \'S\'.
thinSVDC :: Matrix (Complex Double) -> (Matrix (Complex Double), Vector Double, Matrix (Complex Double))
thinSVDC = thinSVDAux zgesvd "thinSVDC"

-- | Thin SVD of a real matrix, using LAPACK's /dgesdd/ with jobz == \'S\'.
thinSVDRd :: Matrix Double -> (Matrix Double, Vector Double, Matrix Double)
thinSVDRd = thinSVDAux dgesdd "thinSVDRdd"

-- | Thin SVD of a complex matrix, using LAPACK's /zgesdd/ with jobz == \'S\'.
thinSVDCd :: Matrix (Complex Double) -> (Matrix (Complex Double), Vector Double, Matrix (Complex Double))
thinSVDCd = thinSVDAux zgesdd "thinSVDCdd"

thinSVDAux f st x = unsafePerformIO $ do
    a <- copy ColumnMajor x
    u <- createMatrix ColumnMajor r q
    s <- createVector q
    v <- createMatrix ColumnMajor q c
    f # a # u # s # v #| st
    return (u,s,v)
  where
    r = rows x
    c = cols x
    q = min r c


-- | Singular values of a real matrix, using LAPACK's /dgesvd/ with jobu == jobvt == \'N\'.
svR :: Matrix Double -> Vector Double
svR = svAux dgesvd "svR"

-- | Singular values of a complex matrix, using LAPACK's /zgesvd/ with jobu == jobvt == \'N\'.
svC :: Matrix (Complex Double) -> Vector Double
svC = svAux zgesvd "svC"

-- | Singular values of a real matrix, using LAPACK's /dgesdd/ with jobz == \'N\'.
svRd :: Matrix Double -> Vector Double
svRd = svAux dgesdd "svRd"

-- | Singular values of a complex matrix, using LAPACK's /zgesdd/ with jobz == \'N\'.
svCd :: Matrix (Complex Double) -> Vector Double
svCd = svAux zgesdd "svCd"

svAux f st x = unsafePerformIO $ do
    a <- copy ColumnMajor x
    s <- createVector q
    g # a # s #| st
    return s
  where
    r = rows x
    c = cols x
    q = min r c
    g ra ca xra xca pa nb pb = f ra ca xra xca pa 0 0 0 0 nullPtr nb pb 0 0 0 0 nullPtr


-- | Singular values and all right singular vectors of a real matrix, using LAPACK's /dgesvd/ with jobu == \'N\' and jobvt == \'A\'.
rightSVR :: Matrix Double -> (Vector Double, Matrix Double)
rightSVR = rightSVAux dgesvd "rightSVR"

-- | Singular values and all right singular vectors of a complex matrix, using LAPACK's /zgesvd/ with jobu == \'N\' and jobvt == \'A\'.
rightSVC :: Matrix (Complex Double) -> (Vector Double, Matrix (Complex Double))
rightSVC = rightSVAux zgesvd "rightSVC"

rightSVAux f st x = unsafePerformIO $ do
    a <- copy ColumnMajor x
    s <- createVector q
    v <- createMatrix ColumnMajor c c
    g # a # s # v #| st
    return (s,v)
  where
    r = rows x
    c = cols x
    q = min r c
    g ra ca xra xca pa = f ra ca xra xca pa 0 0 0 0 nullPtr


-- | Singular values and all left singular vectors of a real matrix, using LAPACK's /dgesvd/  with jobu == \'A\' and jobvt == \'N\'.
leftSVR :: Matrix Double -> (Matrix Double, Vector Double)
leftSVR = leftSVAux dgesvd "leftSVR"

-- | Singular values and all left singular vectors of a complex matrix, using LAPACK's /zgesvd/ with jobu == \'A\' and jobvt == \'N\'.
leftSVC :: Matrix (Complex Double) -> (Matrix (Complex Double), Vector Double)
leftSVC = leftSVAux zgesvd "leftSVC"

leftSVAux f st x = unsafePerformIO $ do
    a <- copy ColumnMajor x
    u <- createMatrix ColumnMajor r r
    s <- createVector q
    g # a # u # s #| st
    return (u,s)
  where
    r = rows x
    c = cols x
    q = min r c
    g ra ca xra xca pa ru cu xru xcu pu nb pb = f ra ca xra xca pa ru cu xru xcu pu nb pb 0 0 0 0 nullPtr

-----------------------------------------------------------------------------

foreign import ccall unsafe "eig_l_R" dgeev :: R ::> R ::> C :> R ::> Ok
foreign import ccall unsafe "eig_l_C" zgeev :: C ::> C ::> C :> C ::> Ok
foreign import ccall unsafe "eig_l_S" dsyev :: CInt -> R :> R ::> Ok
foreign import ccall unsafe "eig_l_H" zheev :: CInt -> R :> C ::> Ok

eigAux f st m = unsafePerformIO $ do
    a <- copy ColumnMajor m
    l <- createVector r
    v <- createMatrix ColumnMajor r r
    g # a # l # v #| st
    return (l,v)
  where
    r = rows m
    g ra ca xra xca pa = f ra ca xra xca pa 0 0 0 0 nullPtr


-- | Eigenvalues and right eigenvectors of a general complex matrix, using LAPACK's /zgeev/.
-- The eigenvectors are the columns of v. The eigenvalues are not sorted.
eigC :: Matrix (Complex Double) -> (Vector (Complex Double), Matrix (Complex Double))
eigC = eigAux zgeev "eigC"

eigOnlyAux f st m = unsafePerformIO $ do
    a <- copy ColumnMajor m
    l <- createVector r
    g # a # l #| st
    return l
  where
    r = rows m
    g ra ca xra xca pa nl pl = f ra ca xra xca pa 0 0 0 0 nullPtr nl pl 0 0 0 0 nullPtr

-- | Eigenvalues of a general complex matrix, using LAPACK's /zgeev/ with jobz == \'N\'.
-- The eigenvalues are not sorted.
eigOnlyC :: Matrix (Complex Double) -> Vector (Complex Double)
eigOnlyC = eigOnlyAux zgeev "eigOnlyC"

-- | Eigenvalues and right eigenvectors of a general real matrix, using LAPACK's /dgeev/.
-- The eigenvectors are the columns of v. The eigenvalues are not sorted.
eigR :: Matrix Double -> (Vector (Complex Double), Matrix (Complex Double))
eigR m = (s', v'')
    where (s,v) = eigRaux m
          s' = fixeig1 s
          v' = toRows $ trans v
          v'' = fromColumns $ fixeig (toList s') v'

eigRaux :: Matrix Double -> (Vector (Complex Double), Matrix Double)
eigRaux m = unsafePerformIO $ do
    a <- copy ColumnMajor m
    l <- createVector r
    v <- createMatrix ColumnMajor r r
    g # a # l # v #| "eigR"
    return (l,v)
  where
    r = rows m
    g ra ca xra xca pa = dgeev ra ca xra xca pa 0 0 0 0 nullPtr

fixeig1 s = toComplex' (subVector 0 r (asReal s), subVector r r (asReal s))
    where r = dim s

fixeig  []  _ =  []
fixeig [_] [v] = [comp' v]
fixeig ((r1:+i1):(r2:+i2):r) (v1:v2:vs)
    | r1 == r2 && i1 == (-i2) = toComplex' (v1,v2) : toComplex' (v1, mapVector negate v2) : fixeig r vs
    | otherwise = comp' v1 : fixeig ((r2:+i2):r) (v2:vs)
fixeig _ _ = error "fixeig with impossible inputs"


-- | Eigenvalues of a general real matrix, using LAPACK's /dgeev/ with jobz == \'N\'.
-- The eigenvalues are not sorted.
eigOnlyR :: Matrix Double -> Vector (Complex Double)
eigOnlyR = fixeig1 . eigOnlyAux dgeev "eigOnlyR"


-----------------------------------------------------------------------------

eigSHAux f st m = unsafePerformIO $ do
    l <- createVector r
    v <- copy ColumnMajor m
    f # l # v #| st
    return (l,v)
  where
    r = rows m

-- | Eigenvalues and right eigenvectors of a symmetric real matrix, using LAPACK's /dsyev/.
-- The eigenvectors are the columns of v.
-- The eigenvalues are sorted in descending order (use 'eigS'' for ascending order).
eigS :: Matrix Double -> (Vector Double, Matrix Double)
eigS m = (s', fliprl v)
    where (s,v) = eigS' m
          s' = fromList . reverse . toList $  s

-- | 'eigS' in ascending order
eigS' :: Matrix Double -> (Vector Double, Matrix Double)
eigS' = eigSHAux (dsyev 1) "eigS'"

-- | Eigenvalues and right eigenvectors of a hermitian complex matrix, using LAPACK's /zheev/.
-- The eigenvectors are the columns of v.
-- The eigenvalues are sorted in descending order (use 'eigH'' for ascending order).
eigH :: Matrix (Complex Double) -> (Vector Double, Matrix (Complex Double))
eigH m = (s', fliprl v)
  where
    (s,v) = eigH' m
    s' = fromList . reverse . toList $  s

-- | 'eigH' in ascending order
eigH' :: Matrix (Complex Double) -> (Vector Double, Matrix (Complex Double))
eigH' = eigSHAux (zheev 1) "eigH'"


-- | Eigenvalues of a symmetric real matrix, using LAPACK's /dsyev/ with jobz == \'N\'.
-- The eigenvalues are sorted in descending order.
eigOnlyS :: Matrix Double -> Vector Double
eigOnlyS = vrev . fst. eigSHAux (dsyev 0) "eigS'"

-- | Eigenvalues of a hermitian complex matrix, using LAPACK's /zheev/ with jobz == \'N\'.
-- The eigenvalues are sorted in descending order.
eigOnlyH :: Matrix (Complex Double) -> Vector Double
eigOnlyH = vrev . fst. eigSHAux (zheev 0) "eigH'"

vrev = flatten . flipud . reshape 1

-----------------------------------------------------------------------------
foreign import ccall unsafe "linearSolveR_l" dgesv :: R ::> R ::> Ok
foreign import ccall unsafe "linearSolveC_l" zgesv :: C ::> C ::> Ok

linearSolveSQAux g f st a b
    | n1==n2 && n1==r = unsafePerformIO . g $ do
        a' <- copy ColumnMajor a
        s  <- copy ColumnMajor b
        f # a' # s #| st
        return s
    | otherwise = error $ st ++ " of nonsquare matrix"
  where
    n1 = rows a
    n2 = cols a
    r  = rows b

-- | Solve a real linear system (for square coefficient matrix and several right-hand sides) using the LU decomposition, based on LAPACK's /dgesv/. For underconstrained or overconstrained systems use 'linearSolveLSR' or 'linearSolveSVDR'. See also 'lusR'.
linearSolveR :: Matrix Double -> Matrix Double -> Matrix Double
linearSolveR a b = linearSolveSQAux id dgesv "linearSolveR" a b

mbLinearSolveR :: Matrix Double -> Matrix Double -> Maybe (Matrix Double)
mbLinearSolveR a b = linearSolveSQAux mbCatch dgesv "linearSolveR" a b


-- | Solve a complex linear system (for square coefficient matrix and several right-hand sides) using the LU decomposition, based on LAPACK's /zgesv/. For underconstrained or overconstrained systems use 'linearSolveLSC' or 'linearSolveSVDC'. See also 'lusC'.
linearSolveC :: Matrix (Complex Double) -> Matrix (Complex Double) -> Matrix (Complex Double)
linearSolveC a b = linearSolveSQAux id zgesv "linearSolveC" a b

mbLinearSolveC :: Matrix (Complex Double) -> Matrix (Complex Double) -> Maybe (Matrix (Complex Double))
mbLinearSolveC a b = linearSolveSQAux mbCatch zgesv "linearSolveC" a b

--------------------------------------------------------------------------------
foreign import ccall unsafe "cholSolveR_l" dpotrs  :: R ::> R ::> Ok
foreign import ccall unsafe "cholSolveC_l" zpotrs  :: C ::> C ::> Ok


linearSolveSQAux2 g f st a b
    | n1==n2 && n1==r = unsafePerformIO . g $ do
        s <- copy ColumnMajor b
        f # a # s #| st
        return s
    | otherwise = error $ st ++ " of nonsquare matrix"
  where
    n1 = rows a
    n2 = cols a
    r  = rows b

-- | Solves a symmetric positive definite system of linear equations using a precomputed Cholesky factorization obtained by 'cholS'.
cholSolveR :: Matrix Double -> Matrix Double -> Matrix Double
cholSolveR a b = linearSolveSQAux2 id dpotrs "cholSolveR" (fmat a) b

-- | Solves a Hermitian positive definite system of linear equations using a precomputed Cholesky factorization obtained by 'cholH'.
cholSolveC :: Matrix (Complex Double) -> Matrix (Complex Double) -> Matrix (Complex Double)
cholSolveC a b = linearSolveSQAux2 id zpotrs "cholSolveC" (fmat a) b

-----------------------------------------------------------------------------------

foreign import ccall unsafe "linearSolveLSR_l"   dgels ::           R ::> R ::> Ok
foreign import ccall unsafe "linearSolveLSC_l"   zgels ::           C ::> C ::> Ok
foreign import ccall unsafe "linearSolveSVDR_l" dgelss :: Double -> R ::> R ::> Ok
foreign import ccall unsafe "linearSolveSVDC_l" zgelss :: Double -> C ::> C ::> Ok

linearSolveAux f st a b
    | m == rows b = unsafePerformIO $ do
        a' <- copy ColumnMajor a
        r  <- createMatrix ColumnMajor (max m n) nrhs
        setRect 0 0 b r
        f # a' # r #| st
        return r
    | otherwise = error $ "different number of rows in linearSolve ("++st++")"
  where
    m = rows a
    n = cols a
    nrhs = cols b

-- | Least squared error solution of an overconstrained real linear system, or the minimum norm solution of an underconstrained system, using LAPACK's /dgels/. For rank-deficient systems use 'linearSolveSVDR'.
linearSolveLSR :: Matrix Double -> Matrix Double -> Matrix Double
linearSolveLSR a b = subMatrix (0,0) (cols a, cols b) $
                     linearSolveAux dgels "linearSolverLSR" a b

-- | Least squared error solution of an overconstrained complex linear system, or the minimum norm solution of an underconstrained system, using LAPACK's /zgels/. For rank-deficient systems use 'linearSolveSVDC'.
linearSolveLSC :: Matrix (Complex Double) -> Matrix (Complex Double) -> Matrix (Complex Double)
linearSolveLSC a b = subMatrix (0,0) (cols a, cols b) $
                     linearSolveAux zgels "linearSolveLSC" a b

-- | Minimum norm solution of a general real linear least squares problem Ax=B using the SVD, based on LAPACK's /dgelss/. Admits rank-deficient systems but it is slower than 'linearSolveLSR'. The effective rank of A is determined by treating as zero those singular valures which are less than rcond times the largest singular value. If rcond == Nothing machine precision is used.
linearSolveSVDR :: Maybe Double   -- ^ rcond
                -> Matrix Double  -- ^ coefficient matrix
                -> Matrix Double  -- ^ right hand sides (as columns)
                -> Matrix Double  -- ^ solution vectors (as columns)
linearSolveSVDR (Just rcond) a b = subMatrix (0,0) (cols a, cols b) $
                                   linearSolveAux (dgelss rcond) "linearSolveSVDR" a b
linearSolveSVDR Nothing a b = linearSolveSVDR (Just (-1)) a b

-- | Minimum norm solution of a general complex linear least squares problem Ax=B using the SVD, based on LAPACK's /zgelss/. Admits rank-deficient systems but it is slower than 'linearSolveLSC'. The effective rank of A is determined by treating as zero those singular valures which are less than rcond times the largest singular value. If rcond == Nothing machine precision is used.
linearSolveSVDC :: Maybe Double            -- ^ rcond
                -> Matrix (Complex Double) -- ^ coefficient matrix
                -> Matrix (Complex Double) -- ^ right hand sides (as columns)
                -> Matrix (Complex Double) -- ^ solution vectors (as columns)
linearSolveSVDC (Just rcond) a b = subMatrix (0,0) (cols a, cols b) $
                                   linearSolveAux (zgelss rcond) "linearSolveSVDC" a b
linearSolveSVDC Nothing a b = linearSolveSVDC (Just (-1)) a b

-----------------------------------------------------------------------------------

foreign import ccall unsafe "chol_l_H" zpotrf :: C ::> Ok
foreign import ccall unsafe "chol_l_S" dpotrf :: R ::> Ok

cholAux f st a = do
    r <- copy ColumnMajor a
    f # r #| st
    return r

-- | Cholesky factorization of a complex Hermitian positive definite matrix, using LAPACK's /zpotrf/.
cholH :: Matrix (Complex Double) -> Matrix (Complex Double)
cholH = unsafePerformIO . cholAux zpotrf "cholH"

-- | Cholesky factorization of a real symmetric positive definite matrix, using LAPACK's /dpotrf/.
cholS :: Matrix Double -> Matrix Double
cholS =  unsafePerformIO . cholAux dpotrf "cholS"

-- | Cholesky factorization of a complex Hermitian positive definite matrix, using LAPACK's /zpotrf/ ('Maybe' version).
mbCholH :: Matrix (Complex Double) -> Maybe (Matrix (Complex Double))
mbCholH = unsafePerformIO . mbCatch . cholAux zpotrf "cholH"

-- | Cholesky factorization of a real symmetric positive definite matrix, using LAPACK's /dpotrf/  ('Maybe' version).
mbCholS :: Matrix Double -> Maybe (Matrix Double)
mbCholS =  unsafePerformIO . mbCatch . cholAux dpotrf "cholS"

-----------------------------------------------------------------------------------

type TMVM t = t ::> t :> t ::> Ok

foreign import ccall unsafe "qr_l_R" dgeqr2 :: R :> R ::> Ok
foreign import ccall unsafe "qr_l_C" zgeqr2 :: C :> C ::> Ok

-- | QR factorization of a real matrix, using LAPACK's /dgeqr2/.
qrR :: Matrix Double -> (Matrix Double, Vector Double)
qrR = qrAux dgeqr2 "qrR"

-- | QR factorization of a complex matrix, using LAPACK's /zgeqr2/.
qrC :: Matrix (Complex Double) -> (Matrix (Complex Double), Vector (Complex Double))
qrC = qrAux zgeqr2 "qrC"

qrAux f st a = unsafePerformIO $ do
    r <- copy ColumnMajor a
    tau <- createVector mn
    f # tau # r #| st
    return (r,tau)
  where
    m = rows a
    n = cols a
    mn = min m n

foreign import ccall unsafe "c_dorgqr" dorgqr :: R :> R ::> Ok
foreign import ccall unsafe "c_zungqr" zungqr :: C :> C ::> Ok

-- | build rotation from reflectors
qrgrR :: Int -> (Matrix Double, Vector Double) -> Matrix Double
qrgrR = qrgrAux dorgqr "qrgrR"
-- | build rotation from reflectors
qrgrC :: Int -> (Matrix (Complex Double), Vector (Complex Double)) -> Matrix (Complex Double)
qrgrC = qrgrAux zungqr "qrgrC"

qrgrAux f st n (a, tau) = unsafePerformIO $ do
    res <- copy ColumnMajor (sliceMatrix (0,0) (rows a,n) a)
    f # (subVector 0 n tau') # res #| st
    return res
  where
    tau' = vjoin [tau, constantD 0 n]

-----------------------------------------------------------------------------------
foreign import ccall unsafe "hess_l_R" dgehrd :: R :> R ::> Ok
foreign import ccall unsafe "hess_l_C" zgehrd :: C :> C ::> Ok

-- | Hessenberg factorization of a square real matrix, using LAPACK's /dgehrd/.
hessR :: Matrix Double -> (Matrix Double, Vector Double)
hessR = hessAux dgehrd "hessR"

-- | Hessenberg factorization of a square complex matrix, using LAPACK's /zgehrd/.
hessC :: Matrix (Complex Double) -> (Matrix (Complex Double), Vector (Complex Double))
hessC = hessAux zgehrd "hessC"

hessAux f st a = unsafePerformIO $ do
    r <- copy ColumnMajor a
    tau <- createVector (mn-1)
    f # tau # r #| st
    return (r,tau)
  where
    m = rows a
    n = cols a
    mn = min m n

-----------------------------------------------------------------------------------
foreign import ccall unsafe "schur_l_R" dgees :: R ::> R ::> Ok
foreign import ccall unsafe "schur_l_C" zgees :: C ::> C ::> Ok

-- | Schur factorization of a square real matrix, using LAPACK's /dgees/.
schurR :: Matrix Double -> (Matrix Double, Matrix Double)
schurR = schurAux dgees "schurR"

-- | Schur factorization of a square complex matrix, using LAPACK's /zgees/.
schurC :: Matrix (Complex Double) -> (Matrix (Complex Double), Matrix (Complex Double))
schurC = schurAux zgees "schurC"

schurAux f st a = unsafePerformIO $ do
    u <- createMatrix ColumnMajor n n
    s <- copy ColumnMajor a
    f # u # s #| st
    return (u,s)
  where
    n = rows a

-----------------------------------------------------------------------------------
foreign import ccall unsafe "lu_l_R" dgetrf :: R :> R ::> Ok
foreign import ccall unsafe "lu_l_C" zgetrf :: R :> C ::> Ok

-- | LU factorization of a general real matrix, using LAPACK's /dgetrf/.
luR :: Matrix Double -> (Matrix Double, [Int])
luR = luAux dgetrf "luR"

-- | LU factorization of a general complex matrix, using LAPACK's /zgetrf/.
luC :: Matrix (Complex Double) -> (Matrix (Complex Double), [Int])
luC = luAux zgetrf "luC"

luAux f st a = unsafePerformIO $ do
    lu <- copy ColumnMajor a
    piv <- createVector (min n m)
    f # piv # lu #| st
    return (lu, map (pred.round) (toList piv))
  where
    n = rows a
    m = cols a

-----------------------------------------------------------------------------------

foreign import ccall unsafe "luS_l_R" dgetrs :: R ::> R :> R ::> Ok
foreign import ccall unsafe "luS_l_C" zgetrs :: C ::> R :> C ::> Ok

-- | Solve a real linear system from a precomputed LU decomposition ('luR'), using LAPACK's /dgetrs/.
lusR :: Matrix Double -> [Int] -> Matrix Double -> Matrix Double
lusR a piv b = lusAux dgetrs "lusR" (fmat a) piv b

-- | Solve a real linear system from a precomputed LU decomposition ('luC'), using LAPACK's /zgetrs/.
lusC :: Matrix (Complex Double) -> [Int] -> Matrix (Complex Double) -> Matrix (Complex Double)
lusC a piv b = lusAux zgetrs "lusC" (fmat a) piv b

lusAux f st a piv b
    | n1==n2 && n2==n =unsafePerformIO $ do
         x <- copy ColumnMajor b
         f # a # piv' # x #| st
         return x
    | otherwise = error $ st ++ " on LU factorization of nonsquare matrix"
  where
    n1 = rows a
    n2 = cols a
    n = rows b
    piv' = fromList (map (fromIntegral.succ) piv) :: Vector Double