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changeset 14984:4315a39da4c9 stable

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Do computations with octave_uint64 to avoid overflow * sparse-dmsolve (MSparse<T>::dmsolve_extract): Perform multiplication and comparison in octave_uint64 to avoid overflow.
author Jordi Gutiérrez Hermoso <jordigh@octave.org>
date Thu, 19 Jul 2012 18:08:08 -0400
parents 9e5df4d6cefa
children 93583f8853b4
files liboctave/sparse-dmsolve.cc
diffstat 1 files changed, 11 insertions(+), 2 deletions(-) [+]
line wrap: on
line diff
--- a/liboctave/sparse-dmsolve.cc
+++ b/liboctave/sparse-dmsolve.cc
@@ -33,6 +33,7 @@
 #include "MatrixType.h"
 #include "oct-sort.h"
 #include "oct-locbuf.h"
+#include "oct-inttypes.h"
 
 template <class T>
 static MSparse<T>
@@ -42,9 +43,17 @@
                 octave_idx_type cend, octave_idx_type maxnz = -1,
                 bool lazy = false)
 {
-  octave_idx_type nz = (rend - rst) * (cend - cst);
+  octave_idx_type nr = rend - rst, nc = cend - cst;
   maxnz = (maxnz < 0 ? A.nnz () : maxnz);
-  MSparse<T> B (rend - rst, cend - cst, (nz < maxnz ? nz : maxnz));
+  octave_idx_type nz;
+
+  // Cast to uint64 to handle overflow in this multiplication
+  if (octave_uint64 (nr)*octave_uint64 (nc) < octave_uint64 (maxnz))
+    nz = nr*nz;
+  else
+    nz = maxnz;
+
+  MSparse<T> B (nr, nc, (nz < maxnz ? nz : maxnz));
   // Some sparse functions can support lazy indexing (where elements
   // in the row are in no particular order), even though octave in
   // general can't. For those functions that can using it is a big