# HG changeset patch
# User Polishchuk Vladimir <address@hidden>
# Date 1375805025 -10800
# Node ID 8ff3c01eb743307ebd2263aacb7ca9e109650d78
# Parent  1c2f14a7935d8237db1f85fabe4152a3f1bfa32b
corect bag in svds.m

diff -r 1c2f14a7935d -r 8ff3c01eb743 scripts/sparse/svds.m
--- a/scripts/sparse/svds.m	Mon Aug 05 15:54:56 2013 -0700
+++ b/scripts/sparse/svds.m	Tue Aug 06 19:03:45 2013 +0300
@@ -164,6 +164,10 @@
       b_sigma = b_sigma / max_a;
     endif
 
+    if (!ischar (sigma))
+      norma = normest (b);
+    endif
+
     if (b_sigma == 0)
       ## Find the smallest eigenvalues
       ## The eigenvalues returns by eigs for sigma=0 are symmetric about 0.
@@ -174,6 +178,13 @@
       ## computation scales with k we'd like to avoid doubling k for all
       ## scalar values of sigma.
       b_k = 2 * k;
+      ## Find eigenvalues symmetric about tolerance for get positive rather
+      ## than negative eigenvalues with the same magnitude.
+      if (opts.tol == 0)
+        b_sigma = norma * eps() * 3;
+      else
+        b_sigma = norma * opts.tol;
+      endif
     else
       b_k = k;  # Normal case, find just the k largest eigenvalues
     endif
@@ -188,8 +199,6 @@
 
     if (ischar (sigma))
       norma = max (s);
-    else
-      norma = normest (A);
     endif
     ## We wish to exclude all eigenvalues that are less than zero as these
     ## are artifacts of the way the matrix passed to eigs is formed. There