FFI, Foreign.Marshal.Array, etc.
Hi! I'm playing with the FFI. Could anyone help me with a practical example? I have a function int solve_sys (double **a, int n, double b[]); where a is an array of size n*n and b is an array of size n (it contains the needed result if solve_sys returns 0). How could I wrap it in something like solveSys :: [[Double]] -> [Double] -> [Double] ? -- Setting Orange, Aftermath 38 YOLD 3174 Alexey Beshenov http://beshenov.ru/
On Wednesday 26 November 2008 23:32:58 Alexey Beshenov wrote:
Hi!
I'm playing with the FFI. Could anyone help me with a practical example?
I have a function
int solve_sys (double **a, int n, double b[]);
where a is an array of size n*n and b is an array of size n (it contains the needed result if solve_sys returns 0).
How could I wrap it in something like
solveSys :: [[Double]] -> [Double] -> [Double]
?
Something like this: foreign import ccall "linear.h solve_sys" lSolve :: Ptr (Double) -> Int -> Ptr (Double) -> IO (Int) solveSys :: [[Double]] -> [Double] -> IO() solveSys a b = do aptr <- newArray (concat a) bptr <- newArray b sol <- lSolve aptr n bptr x <- peekArray n bptr free aptr free bptr print x where n = length a Does the trick, but I wonder is there a way to get a function returning [Double]... -- Setting Orange, Aftermath 38 YOLD 3174 Alexey Beshenov http://beshenov.ru/
On Thursday 27 November 2008 01:16:17 Alexey Beshenov wrote:
Something like this:
foreign import ccall "linear.h solve_sys" lSolve :: Ptr (Double) -> Int -> Ptr (Double) -> IO (Int)
solveSys :: [[Double]] -> [Double] -> IO() solveSys a b = do aptr <- newArray (concat a) bptr <- newArray b sol <- lSolve aptr n bptr x <- peekArray n bptr free aptr free bptr print x where n = length a
Does the trick, but I wonder is there a way to get a function returning [Double]...
Eh, I have to do unsafePerformIO. Sorry about that, I'm quite new to Haskell :-I -- Setting Orange, Aftermath 38 YOLD 3174 Alexey Beshenov http://beshenov.ru/
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Alexey Beshenov