#15305: Allow natural morphism between tensor products
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Reporter: tscrim | Owner: sage-combinat
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-5.13
Component: coercion | Resolution:
Keywords: tensor product coercion | Merged in:
Authors: Travis Scrimshaw | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: #15309 | Stopgaps:
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Comment (by nthiery):
Replying to [comment:10 nborie]:
> {{{
> def tensor_morphism(t):
> im = [M(R._sets[i].monomial(t[i])) for i,M in enumerate(self._sets)]
> return self.sum_of_terms([(tuple(x[0] for x in cp), B.prod(x[1] for
x in cp))
> for cp in im])
> }}}
In the above, M(...) calls a conversion morphism from R._sets[i] to M.
More often than not, that morphism will be a module_morphism, and thus
have a "on_basis" method. So if we request once for all the morphism, on
could rewrite it as just phi.on_basis(t[i]), avoiding a lot of the
overhead.
Btw: doing this might be easier if one extracts a
"tensor_product_of_morphisms" function.
--
Ticket URL: <http://trac.sagemath.org/ticket/15305#comment:13>
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