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changeset 20603:f61c67865d9f

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Don't return A for inv (A) when A is a singular Diagonal matrix (bug #46103). * dDiagMatrix.cc (inverse), fDiagMatrix.cc (inverse): return octave_Inf for the inverse of a diagonal element whose value is 0. * test/diag-perm.tst: Add tests for new behavior.
author Rik <rik@octave.org>
date Wed, 07 Oct 2015 07:41:44 -0700
parents ea6a1c00763a
children 734d446560a8
files liboctave/array/dDiagMatrix.cc liboctave/array/fDiagMatrix.cc test/diag-perm.tst
diffstat 3 files changed, 9 insertions(+), 8 deletions(-) [+]
line wrap: on
line diff
--- a/liboctave/array/dDiagMatrix.cc	Tue Oct 06 22:14:41 2015 +0200
+++ b/liboctave/array/dDiagMatrix.cc	Wed Oct 07 07:41:44 2015 -0700
@@ -280,10 +280,7 @@
   for (octave_idx_type i = 0; i < len; i++)
     {
       if (elem (i, i) == 0.0)
-        {
-          info = -1;
-          return *this;
-        }
+        retval.elem (i, i) = octave_Inf;
       else
         retval.elem (i, i) = 1.0 / elem (i, i);
     }
--- a/liboctave/array/fDiagMatrix.cc	Tue Oct 06 22:14:41 2015 +0200
+++ b/liboctave/array/fDiagMatrix.cc	Wed Oct 07 07:41:44 2015 -0700
@@ -280,10 +280,7 @@
   for (octave_idx_type i = 0; i < len; i++)
     {
       if (elem (i, i) == 0.0)
-        {
-          info = -1;
-          return *this;
-        }
+        retval.elem (i, i) = octave_Inf;
       else
         retval.elem (i, i) = 1.0 / elem (i, i);
     }
--- a/test/diag-perm.tst	Tue Oct 06 22:14:41 2015 +0200
+++ b/test/diag-perm.tst	Wed Oct 07 07:41:44 2015 -0700
@@ -263,3 +263,10 @@
 %! A = A * I () + A;
 %! A(6, 4) = nan ();
 %! assert (full (D - A), D - full (A));
+
+## inverse preserves diagonal structure even for singular matrices (bug #46103)
+%!test
+%! x = diag (1:3);
+%! assert (inv (x), diag ([1 1/2 1/3]));
+%! x = diag (0:2);
+%! assert (inv (x), diag ([Inf 1 1/2]));