Hi, I naively expected making the zero nxn sparse matrix in Sage to be O(1), and so might you. However:
sage: get_memory_usage() 836.4921875 sage: time a = matrix(QQ, 2^25, sparse=True) Time: CPU 6.79 s, Wall: 6.79 s sage: get_memory_usage() 3908.30078125 sage: time b = matrix(QQ, 2^26, sparse=True) Time: CPU 12.20 s, Wall: 12.20 s sage: get_memory_usage() 10052.4375 If this bugs you, maybe look at http://trac.sagemath.org/sage_trac/ticket/12348 I wouldn't be surprised to find that this is totally my fault for doing something really stupid long ago, like caching matrix space spaces or something. Maybe not, since: sage: time v = b.parent().basis() Traceback (most recent call last): /home/wstein/<ipython console> in <module>() /usr/local/sage/local/lib/python2.6/site-packages/sage/matrix/matrix_space.pyc in basis(self) 939 ] 940 """ --> 941 v = [self.zero_matrix().__copy__() for _ in range(self.dimension())] 942 one = self.base_ring()(1) 943 i = 0 OverflowError: range() result has too many items -- William Stein Professor of Mathematics University of Washington http://wstein.org -- To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org
