From 355eae1c5dcd83be84ae6d3379480b98a675dc08 Mon Sep 17 00:00:00 2001
From: Alberto Ruiz <aruiz@um.es>
Date: Mon, 19 Mar 2012 12:24:53 +0100
Subject: orth

---
 lib/Numeric/LinearAlgebra/Algorithms.hs | 8 ++++++++
 1 file changed, 8 insertions(+)

(limited to 'lib/Numeric/LinearAlgebra/Algorithms.hs')

diff --git a/lib/Numeric/LinearAlgebra/Algorithms.hs b/lib/Numeric/LinearAlgebra/Algorithms.hs
index 435cc5a..9ae5e32 100644
--- a/lib/Numeric/LinearAlgebra/Algorithms.hs
+++ b/lib/Numeric/LinearAlgebra/Algorithms.hs
@@ -64,6 +64,7 @@ module Numeric.LinearAlgebra.Algorithms (
     nullspacePrec,
     nullVector,
     nullspaceSVD,
+    orth,
 -- * Norms
     Normed(..), NormType(..),
     relativeError,
@@ -445,6 +446,13 @@ nullspacePrec t m = nullspaceSVD (Left (t*eps)) m (rightSV m)
 nullVector :: Field t => Matrix t -> Vector t
 nullVector = last . nullspacePrec 1
 
+orth :: Field t => Matrix t -> [Vector t]
+-- ^ Return an orthonormal basis of the range space of a matrix
+orth m = take r $ toColumns u
+  where
+    (u,s,_) = compactSVD m
+    r = ranksv eps (max (rows m) (cols m)) (toList s)
+
 ------------------------------------------------------------------------
 
 {-  Pseudoinverse of a real matrix with the desired tolerance, expressed as a
-- 
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