Fix #282

LAPACK routine dgttrf mutates its inputs per documentation. To prevent
user-visible breakage input vectors must be copied before sending them
to LAPACK.

1 files changed, 3 insertions, 1 deletions

diff --git a/packages/base/src/Internal/LAPACK.hs b/packages/base/src/Internal/LAPACK.hs
index ff55688..27d1f95 100644
--- a/packages/base/src/Internal/LAPACK.hs
+++ b/packages/base/src/Internal/LAPACK.hs
@@ -506,8 +506,10 @@ linearSolveGTAux2 g f st dl d du b
     | ndl  == nd - 1 &&
       ndu  == nd - 1 &&
       nd   == r = unsafePerformIO . g $ do
+        dl' <- head . toRows <$> copy ColumnMajor (fromRows [dl])
+        du' <- head . toRows <$> copy ColumnMajor (fromRows [du])
         s <- copy ColumnMajor b
-        (dl # d # du #! s) f #| st
+        (dl' # d # du' #! s) f #| st
         return s
     | otherwise = error $ st ++ " of nonsquare matrix"
   where