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QQbar should have a coercion from number fields with embedding #5355
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comment:1
This should not be hard. Here is what I propose:
Using the default there would be a coercion possible from K to QQbar; but the first version would allow the user flexibility. |
comment:2
Related: #12715 |
comment:3
We do have
Isn't it enough? What should be simplified is to automatized the embedding into |
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Changed keywords from none to qqbar |
comment:6
There are memory-leak implications on this: Coercions are normally cached on the codomain (in this case QQbar). Having a coercion from a number field K to QQbar would imply a reference from QQbar to K. Some effort is made to not make that reference a strong one right from the start (this is why the coercion framework tries to use weak references to the domain), but you'd have to test this quite carefully. Thanks to the complicated interactions with the (weak) dictionaries, I expect that some indirect memory leaks would be introduced. |
comment:7
Replying to @videlec:
To automate the embedding, what should be the interface, perhaps something like this?
|
If a number field comes with an embedding into the complex numbers, QQbar should allow coercions (or at least conversions) from that number field.
For example:
Currently, this map can already be created using
K.hom([QQbar(a)])
(see #13041).Component: coercion
Keywords: qqbar
Issue created by migration from https://trac.sagemath.org/ticket/5355
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