On Tuesday 17 April 2007 04:30, David Harvey wrote:
> On Apr 16, 2007, at 10:24 PM, Robert Miller wrote:
> > sage: M = Matrix(GF(2), [[1,1,0],[0,0,1]])
> > sage: M.row_space()
> >
> > Vector space of degree 3 and dimension 1 over Finite Field of size 2
> > Basis matrix:
> > [1 1 0]
>
> yeah that's bad.
Agreed. Fix appended. This patch also fixes a bug reported by David Kohel
yesterday via private communication.
Martin
--
name: Martin Albrecht
_pgp: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0x8EF0DC99
_www: http://www.informatik.uni-bremen.de/~malb
_jab: [EMAIL PROTECTED]
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# HG changeset patch
# User 'Martin Albrecht <[EMAIL PROTECTED]>'
# Date 1176797050 -7200
# Node ID ff3d72577e800fcacd3b1e04b8a12602eae9bf66
# Parent 16b5f14db2248aaa025d325d9651fb75fca51c9c
fixed bug where rank wasn't computed correctly
diff -r 16b5f14db224 -r ff3d72577e80 sage/libs/m4ri/packedmatrix.c
--- a/sage/libs/m4ri/packedmatrix.c Tue Apr 17 09:19:04 2007 +0200
+++ b/sage/libs/m4ri/packedmatrix.c Tue Apr 17 10:04:10 2007 +0200
@@ -355,12 +355,12 @@ void rowAddPacked( packedmatrix *m, int
int gaussianPackedDelayed(packedmatrix *m, int startcol, int full) {
int i,j;
- int start, stop=min( m->rows, m->cols);
+ int start; //stop=min( m->rows, m->cols);
int startrow = startcol;
int ii;
int pivots = 0;
- for (i=startcol ; i<stop ; i++) {
+ for (i=startcol ; i<m->cols ; i++) {
for(j=startrow ; j < m->rows; j++) {
if (readPackedCell(m,j,i)) {
diff -r 16b5f14db224 -r ff3d72577e80 sage/matrix/matrix_mod2_dense.pyx
--- a/sage/matrix/matrix_mod2_dense.pyx Tue Apr 17 09:19:04 2007 +0200
+++ b/sage/matrix/matrix_mod2_dense.pyx Tue Apr 17 10:04:10 2007 +0200
@@ -56,6 +56,33 @@ EXAMPLES:
sage: b.echelonize(); b
[1 0 1]
[0 1 0]
+
+TESTS:
+ sage: FF = FiniteField(2)
+ sage: V = VectorSpace(FF,2)
+ sage: v = V([0,1]); v
+ (0, 1)
+ sage: W = V.subspace([v])
+ sage: W
+ Vector space of degree 2 and dimension 1 over Finite Field of size 2
+ Basis matrix:
+ [0 1]
+ sage: v in W
+ True
+
+ sage: M = Matrix(GF(2), [[1,1,0],[0,1,0]])
+ sage: M.row_space()
+ Vector space of degree 3 and dimension 2 over Finite Field of size 2
+ Basis matrix:
+ [1 0 0]
+ [0 1 0]
+
+ sage: M = Matrix(GF(2), [[1,1,0],[0,0,1]])
+ sage: M.row_space()
+ Vector space of degree 3 and dimension 2 over Finite Field of size 2
+ Basis matrix:
+ [1 1 0]
+ [0 0 1]
TODO:
- make linbox frontend and use it
@@ -627,7 +654,7 @@ cdef class Matrix_mod2_dense(matrix_dens
_sig_on
r = simpleFourRussiansPackedFlex(self._entries, 1, k)
_sig_off
-
+
self.cache('in_echelon_form',True)
self.cache('rank', r)
self.cache('pivots', self._pivots())
