On Sun, Nov 16, 2014 at 4:08 PM, Vincent Delecroix <20100.delecr...@gmail.com> wrote: > 2014-11-16 5:42 UTC−07:00, Fredrik Johansson <fredrik.johans...@gmail.com>: >> >> >> On Sunday, November 16, 2014 5:45:01 AM UTC+1, vdelecroix wrote: >>> >>> Hello, >>> >>> We currently have two much implementation of 2x2 matrices. I found at >>> least three that leads to distinct element classes >>> >>> sage: M1 = SL2Z >>> sage: M2 = MatrixSpace(ZZ,2) >>> sage: from sage.matrix.matrix_integer_2x2 import MatrixSpace_ZZ_2x2 >>> sage: M3 = MatrixSpace_ZZ_2x2() >>> >>> sage: m1 = M1([2,1,1,1]) >>> sage: m2 = M2([2,1,1,1]) >>> sage: m3 = M3([2,1,1,1]) >>> >>> SL2Z is mostly used in code related to modular forms. And I found only >>> one place where MatrixSpace_ZZ_2x2 is used. I would like to: >>> - try to remove the special class we have for SL2Z (or at least >>> inherit from the generic 2x2 integer which is faster and interacts >>> nicely with the rest of matrix code) >>> - make the MatrixSpace_ZZ_2x2 be the default when we call >>> "MatrixSpace(ZZ,2)". >>> >>> I wanted to ask about opinions before starting. >>> >>> Vincent >>> >>> PS: benchmark >>> >>> sage: %timeit m1**1001 >>> 1000 loops, best of 3: 237 µs per loop >>> sage: %timeit m1*m1 >>> 100000 loops, best of 3: 14.8 µs per loop >>> >>> sage: %timeit m2**1001 >>> 10000 loops, best of 3: 74.4 µs per loop >>> sage: %timeit m2*m2 >>> 100000 loops, best of 3: 4.4 µs per loop >>> >>> sage: %timeit m3**1001 >>> 10000 loops, best of 3: 19.3 µs per loop >>> sage: %timeit m3*m3 >>> 1000000 loops, best of 3: 847 ns per loop >>> >> >> Is this with or without http://trac.sagemath.org/ticket/16803 ? >> >> In C, m**1001 takes 6 µs and m*m takes < 200 ns for me with flint. > > Hello Frederik, > > I did the benchmark on sage-6.4 in which #16803 is already merged. > What do you mean by "in C"?
I mean just calling the flint functions directly in a C program. I'm surprised that there is so much overhead (4 µs) on the Sage side for multiplying two matrices, particularly considering that there seems to be less than 1 µs overhead for multiplying two MatrixSpace_ZZ_2x2. I guess exponentiation doesn't call fmpz_mat_pow at all and just does binary exponentiation on Sage objects. Fredrik -- 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. For more options, visit https://groups.google.com/d/optout.
