From 6dbbf1130a3318a1cc408f948ac15e74090710ec Mon Sep 17 00:00:00 2001
From: Michael Orlitzky <michael@orlitzky.com>
Date: Mon, 4 Feb 2013 20:41:36 -0500
Subject: [PATCH] Add a 2D fixed-point doctest (example) to Vector.hs. Remove
 unused imports.

---
 src/Matrix.hs |  1 -
 src/Vector.hs | 15 ++++++++++++++-
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/src/Matrix.hs b/src/Matrix.hs
index ea44ae9..5b55844 100644
--- a/src/Matrix.hs
+++ b/src/Matrix.hs
@@ -9,7 +9,6 @@ where
 
 import Vector
 import Data.Vector.Fixed (
-  Arity(..),
   Dim,
   Vector,
   (!),
diff --git a/src/Vector.hs b/src/Vector.hs
index b42932c..f55808b 100644
--- a/src/Vector.hs
+++ b/src/Vector.hs
@@ -11,7 +11,6 @@ import Data.List (intercalate)
 import Data.Vector.Fixed (
   Dim,
   Fun(..),
-  N1,
   N2,
   N3,
   N4,
@@ -217,6 +216,20 @@ angle v1 v2 =
 -- constructors, so you can pattern match out the individual
 -- components.
 
+-- | Convenient constructor for 2D vectors.
+--
+--   Examples:
+--
+--   >>> import Roots.Simple
+--   >>> let h = 0.5 :: Double
+--   >>> let g1 (Vn (Vec2D x y)) = 1.0 + h*exp(-(x^2))/(1.0 + y^2)
+--   >>> let g2 (Vn (Vec2D x y)) = 0.5 + h*atan(x^2 + y^2)
+--   >>> let g u = make2d ((g1 u), (g2 u))
+--   >>> let u0 = make2d (1.0, 1.0)
+--   >>> let eps = 1/(10^9)
+--   >>> fixed_point g eps u0
+--   (1.0728549599342185,1.0820591495686167)
+--
 data Vec2D a = Vec2D a a
 type instance Dim Vec2D = N2
 instance Vector Vec2D a where
-- 
2.43.2