Add another example for forward_substitute.

diff --git a/src/Linear/System.hs b/src/Linear/System.hs
index 58d8d78e7a6fe866751109a1c1dfb1610eeeb728..f49c652e494d769ed4be5e69db9d468abbef8d72 100644 (file)
--- a/src/Linear/System.hs
+++ b/src/Linear/System.hs
@@ -31,6 +31,11 @@ import qualified Algebra.Field as Field
 --   >>> forward_substitute m b
 --   ((1.0),(0.0))
 --
+--   >>> let m = fromList [[4,0],[0,2]] :: Mat2 Double
+--   >>> let b = vec2d (2, 1.5 :: Double)
+--   >>> forward_substitute m b
+--   ((0.5),(0.75))
+--
 forward_substitute :: forall a m. (Field.C a, Arity m)
                    => Mat m m a
                    -> Mat m N1 a