Dear all, I have written some code (toy implementation) in sage. It could be useful for other people as well. So now I am wondering whether I should make an effort to implement it meeting the sage-devel standards. How good are the chances for such a project to be included in the sage source code?
So here is the project: LatticeWithIsometry where a lattice L is a free abelian group equipped with a non-degenerate symmetric bilinear form (ZZ or QQ valued). An isometry f is a ZZ-Module automorphism preserving the bilinear form. So we want to model (L,f) Functionality: - constructor for ideal lattices - that is lattices (+isometries) cooked up from irreducible reciprocal polynomials (think of the cyclotomic polynomials) and their trace forms - gluing of lattices. That is taking a direct sum (L,f) + (N,g) and getting integral overlattices compatible with (f,g). - describing the action of the isometry on sub/super lattices such as the dual lattice L' or quotients such as the discriminant group L'/L - a method to decide whether a given isometry of a hyperbolic lattice preserves a chamber of the positive cone cut out by the root hyperplanes (this relates to Weyl groups) A possible reference for this is: http://www.math.harvard.edu/~ctm/papers/home/text/papers/pos/pos.pdf My personal aim in this is to model integral hodge isometries of K3 surfaces or IHSMs. I also wonder how this would fit into the sage world. Should this inherit from quadratic forms ? (feels wrong) or is there some lattice class out there? Since I am new in sage, writing a whole lattice class seems to be too much work for me (and well above my level of experience). There seem to have been previous discussions about lattices e.g. Discussion in Sage devel: https://groups.google.com/forum/#!searchin/sage-devel/lattice|sort:relevance/sage-devel/OO0ADcuraqE/mUG5_UrYFD4J and https://groups.google.com/forum/#!searchin/sage-devel/lattice$20-poset|sort:relevance/sage-devel/KTmqIcav9e4/wWdiQ71PWVYJ There also seem to have been previous attempts for implementing lattices such as https://trac.sagemath.org/ticket/11940 https://trac.sagemath.org/ticket/15976 What has happened to them? Or the rather incomplete FreeQuadraticModule http://doc.sagemath.org/html/en/reference/modules/sage/modules/free_quadratic_module.html which claims to have non trivial functionality over ZZ - I couldn't find any. Simon -- 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 https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
