For non-scalar multiplies, it checks the types _and_ the parents. For scalar operations, these will be implemented as actions, and hopefully the way it will be set up, once discovery is done the path will be very quick.
I agree with points (1) and (2) below. Vector.__mull__() should eventually be eliminated. On Jun 21, 2007, at 7:43 AM, David Harvey wrote: > Ok I gdb'd this, and I can tell you exactly where the problem is, but > I can't tell you how to fix it, because I don't think anyone has > written down the rules for how this should work. Or maybe they have > and I don't know where to look. > > In structure/element.pyx, the __mul__ method of class Vector is being > called. By inspecting the *type* of its arguments it determines that > this is a vector*matrix operation, and calls the > _vector_times_matrix_c() method on the matrix. However it looks like > the implementation of _vector_times_matrix_c() on > Matrix_rational_dense *assumes* that the vector is over Q, i.e. is a > Vector_rational_dense. It just does a C pointer cast to do this, no > type checking. Crash. > > So my feeling is that: > (1) the vector_times_matrix_c() function should be able to assume > that the vector is over the same ring as the matrix, > (2) therefore there is a bug in Vector.__mul__(). It shouldn't just > be checking the types, it should also be checking the base rings, and > if they don't agree, some coercion should be kicking in. > > Thoughts? > > My only concern is the whole question about multiple representation > formats... like what happens if a parent (say vectors over some ring) > has more than one way of representing elements. Is Vector.__mul__ > responsible for the conversion in this case, or is it the vector/ > matrix multiply operation? > > david > > On Jun 21, 2007, at 3:00 AM, Gonzalo Tornaria wrote: > >> >> --------------------------------------------------------------------- >> - >> | SAGE Version 2.6, Release Date: >> 2007-06-02 | >> | Type notebook() for the GUI, and license() for >> information. | >> --------------------------------------------------------------------- >> - >> >> sage: vector(ZZ[x],[1])*matrix(QQ,1,1,[1]) >> *** glibc detected *** sage.bin: realloc(): invalid old size: >> 0x00007fff27379990 *** > > > --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://sage.scipy.org/sage/ and http://modular.math.washington.edu/sage/ -~----------~----~----~----~------~----~------~--~---
