Changes between Version 12 and Version 20 of Ticket #17671
 Timestamp:
 01/28/15 12:51:14 (5 years ago)
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Ticket #17671

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#17673
to#17673, #17675

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1d84c4a9160533338cb19a8df2351cd0fc9d79d0
toc6db5f832b23d29026019de5306472a25e591279

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Ticket #17671 – Description
v12 v20 17 17 2. We fix the `xgcd` for trivial cases in `rings.polynomial.polynomial_element_generic.Polynomial_generic_field` in order that `gcd` and `xgcd` agree for them. 18 18 3. We introduce a generic test `_test_gcd_vs_xgcd` in the category `PrincipalIdealDomains` to ensure the compatibility of `gcd` and `xgcd`. 19 20 QUESTIONS: 21 22 1. In the previous implementation of gcd in `sage.categories.fields` there is a backward compatibility weirdness 19 4. Modify the previous behavior for real numbers (which was present because of mysterious backward compatibility reasons) 23 20 {{{ 24 21 sage: gcd(2.0, 4.0) … … 27 24 Integer Ring 28 25 }}} 29 For the moment, I propagated this to `lcm` and `xgcd`. 26 Now we have 27 {{{ 28 sage: gcd(2.0, 4.0) 29 1.00000000000000 30 sage: gcd(2.0, 4.0).parent() 31 Real Field with 53 bits of precision 32 }}} 30 33 31 2. There is a method `xgcd` implemented for univariate polynomial over ZZ. ~~This is not a proper name since it has nothing to do with `gcd`~~ This might not be the best name since the first term is not the gcd in general (see [https://groups.google.com/forum/#!topic/sagedevel/JV8fCPUqTzo this sagedevel thread]) 34 35 Note: 36 37 There is a method `xgcd` implemented for univariate polynomial over ZZ. ~~This is not a proper name since it has nothing to do with `gcd`~~ This might not be the best name since the first term is not the gcd in general (see [https://groups.google.com/forum/#!topic/sagedevel/JV8fCPUqTzo this sagedevel thread] and #17674)