On Thu, Nov 26, 2009 at 05:29:47AM -0800, YannLC wrote:
> If you only want linear terms, you can also use an univariate
> polynomial ring
>
> just treat x^i as x_i.
>
> it's lightning fast and allow you to easily access coefficients.
Variant:
sage: F =CombinatorialFreeModule(QQ, NonNegativeIntegers())
sage: x = F.basis()
sage: x[3] + 2* x[8]
B[3] + 2*B[8]
sage: f = x[3] + 2* x[8]
sage: f[8]
2
This models more straightforwardly your problem. However, it's
currently (by far) not as fast as polynomials. This slowness will be
fixed as soon as the sparse free module code will have been
generalized to handle FreeModule(QQ, infinity).
Best,
Nicolas
--
Nicolas M. Thiéry "Isil" <nthi...@users.sf.net>
http://Nicolas.Thiery.name/
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