added simpler devel example

1 files changed, 44 insertions, 0 deletions

diff --git a/examples/devel/ej1/wrappers.hs b/examples/devel/ej1/wrappers.hs
new file mode 100644
index 0000000..b329464
--- /dev/null
+++ b/examples/devel/ej1/wrappers.hs
@@ -0,0 +1,44 @@
+{-# LANGUAGE ForeignFunctionInterface #-}
+
+-- $ ghc -O2 --make wrappers.hs functions.c
+
+import Numeric.LinearAlgebra
+import Data.Packed.Development
+import Foreign(Ptr,unsafePerformIO)
+import Foreign.C.Types(CInt)
+
+-----------------------------------------------------
+
+main = do
+    print $ myScale 3.0 (fromList [1..10])
+    print $ myDiag $ (3><5) [1..]
+
+-----------------------------------------------------
+
+foreign import ccall "c_scale_vector"
+    cScaleVector :: Double                -- scale
+                 -> CInt -> Ptr Double    -- argument
+                 -> CInt -> Ptr Double    -- result
+                 -> IO CInt               -- exit code
+
+myScale s x = unsafePerformIO $ do
+    y <- createVector (dim x)
+    app2 (cScaleVector s) vec x vec y "cScaleVector"
+    return y
+
+-----------------------------------------------------
+-- forcing row order
+
+foreign import ccall "c_diag"
+    cDiag :: CInt -> CInt -> Ptr Double  -- argument
+          -> CInt -> Ptr Double          -- result1
+          -> CInt -> CInt -> Ptr Double  -- result2
+          -> IO CInt                     -- exit code
+
+myDiag m = unsafePerformIO $ do
+    y <- createVector (min r c)
+    z <- createMatrix RowMajor r c
+    app3 cDiag mat (cmat m) vec y mat z "cDiag"
+    return (y,z)
+  where r = rows m
+        c = cols m