Maybe my conception of a free module is different then: In the sense of http://en.wikipedia.org/wiki/Free_module, I want an R-module M with basis E ⊆ M, where R = ZZ and E is a set of vectors in RR^n. R is what I refer to as "coefficient ring" (or "scalar ring"), and it makes a big difference whether this is integers (which results in a classic point lattice) or real numbers (which results in a subspace). Was FreeModule (or FreeModule_submodule_with_basis_pid, specifically) ever meant to be used for the former case?
Thanks, Jan On Tuesday, June 5, 2012 1:56:36 PM UTC+2, John Cremona wrote: > > I don't see what is wrong in your example. If you want vectors in > RR^2, replace ZZ^2 with RR^2 in the input line. > > John > > On 5 June 2012 09:01, Jan Pöschko wrote: > > Hi everyone, > > > > I am working on the Summer of Code Lattices project and ran into a > problem > > when trying to subclass Lattice > from FreeModule_submodule_with_basis_pid. If > > I'm getting it right, the coefficient ring R is to be specified as > parameter > > ambient (in the form R^n), followed by the basis vectors in K^n. Now I > don't > > understand why the basis is coerced to the fraction field of R (if not R > > itself), e.g. > > > > sage: from sage.modules.free_module import > > FreeModule_submodule_with_basis_pid as FMs > > sage: FMs(ZZ^2, [(0.5,0.25), (1.0,0)]) > > Free module of degree 2 and rank 2 over Integer Ring > > User basis matrix: > > [1/2 1/4] > > [ 1 0] > > > > I would like to allow creating lattices of points in RR^n (the real > vector > > space) with integer coefficients (ZZ), which is probably the most common > > form of point lattices. As lattices really are free modules, it would be > > good to inherit from them, but with the basis being kept in RR^n if > given > > therein. > > > > I tried a workaround by disabling checking and echelonization of the > basis > > (see the details of my approach), but this doesn't work actually. > > > > Is there a reason why FreeModule is restricted in this way? Should it be > > patched? Or should lattices subclass from something else? > > > > Thanks, > > Jan > > > > -- > > To post to this group, send an email to [email protected] > > To unsubscribe from this group, send an email to > > [email protected] > > For more options, visit this group at > > http://groups.google.com/group/sage-devel > > URL: http://www.sagemath.org > -- To post to this group, send an email to [email protected] To unsubscribe from this group, send an email to [email protected] For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org
