From 3c226d5d5ceb0781b10d86dcb958846f1cc9b075 Mon Sep 17 00:00:00 2001 From: Michael Orlitzky Date: Tue, 11 Feb 2014 16:10:18 -0500 Subject: [PATCH] Add Linear.Matrix.set_idx. Loosen constraints on the dot product function. --- src/Linear/Matrix.hs | 35 +++++++++++++++++++++++++++++++---- 1 file changed, 31 insertions(+), 4 deletions(-) diff --git a/src/Linear/Matrix.hs b/src/Linear/Matrix.hs index 3d4daab..4d1dceb 100644 --- a/src/Linear/Matrix.hs +++ b/src/Linear/Matrix.hs @@ -662,11 +662,16 @@ vec5d (v,w,x,y,z) = Mat (mk5 (mk1 v) (mk1 w) (mk1 x) (mk1 y) (mk1 z)) scalar :: a -> Mat1 a scalar x = Mat (mk1 (mk1 x)) -dot :: (RealRing.C a, m ~ S t, Arity t) - => Col m a - -> Col m a +-- Get the scalar value out of a 1x1 matrix. +unscalar :: Mat1 a -> a +unscalar (Mat rows) = V.head $ V.head rows + + +dot :: (Ring.C a, Arity m) + => Col (S m) a + -> Col (S m) a -> a -v1 `dot` v2 = ((transpose v1) * v2) !!! (0, 0) +v1 `dot` v2 = unscalar $ ((transpose v1) * v2) -- | The angle between @v1@ and @v2@ in Euclidean space. @@ -969,3 +974,25 @@ reverse2 :: (Arity m, Arity n) => Mat m n a -> Mat m n a reverse2 (Mat rows) = Mat $ V.reverse $ V.map V.reverse rows +-- | Unsafely set the (i,j) element of the given matrix. +-- +-- Examples: +-- +-- >>> let m = fromList [[1,2,3],[4,5,6],[7,8,9]] :: Mat3 Int +-- >>> set_idx m (1,1) 17 +-- ((1,2,3),(4,17,6),(7,8,9)) +-- +set_idx :: forall m n a. + (Arity m, Arity n) + => Mat m n a + -> (Int, Int) + -> a + -> Mat m n a +set_idx matrix (i,j) newval = + imap2 updater matrix + where + updater :: Int -> Int -> a -> a + updater k l existing = + if k == i && l == j + then newval + else existing -- 2.44.2