This is now http://trac.sagemath.org/14627 (needs review)
On Tuesday, May 21, 2013 12:40:00 PM UTC+1, Volker Braun wrote: > > Reposted at the top to increase visiblitiy (see > https://groups.google.com/d/msg/sage-devel/5PdRIUic2Es/l0yDYLG_8qIJ) > > The sage matrices use unsigned long for the mod_int datatype. This does > not fit into a (signed) python int, so whenever it reaches Python > (assigning to a Python variable, or passing as an argument to a non-cdef > function) it gets converted to a Python arbitrary-precision integer. This > wastes quite a bit of time when creating it and gets worse once you start > doing arithmetic: > > -------------------------------------- > ctypedef unsigned long mod_int # this is how we define it > > cpdef caster_slow(): > cdef int i > foo = None > for i in range(10000000): > foo = <mod_int>(1.0) > > cpdef caster_fast(): > cdef int i > foo = None > for i in range(10000000): > foo = <int>(1.0) > -------------------------------------- > > Then we get > > sage: timeit('caster_slow()') > 5 loops, best of 3: 137 ms per loop > sage: timeit('caster_fast()') > 25 loops, best of 3: 34.4 ms per loop > > Should we just switch to (signed) long? This wastes one bit (factor of 2) > of maximum modulus length, but at least for now we define MAX_MODULUS = > 2**23 so this wouldn't be an issue. > > > -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at http://groups.google.com/group/sage-devel?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
