Hi,
Let K be a quadratic number field (let say K = QuadraticField(2)).
There are "natural morphisms" implemented in Cython from ZZ to QQ and
from QQ to K. There is also an other way, somewhat more direct, to go
from ZZ to K. But at the end it is 10 times faster to go the first way
and Sage does not choose it!
{{{
sage: K.<sqrt2>=QuadraticField(2)
sage: f = K.coerce_map_from(ZZ)
sage: g = K.coerce_map_from(QQ) * QQ.coerce_map_from(ZZ)
sage: timeit('f(1)')
625 loops, best of 3: 13.8 µs per loop
sage: timeit('g(1)')
625 loops, best of 3: 1.29 µs per loop
}}}
What can I do to make Sage chooses the undirect way ? In some sense a
composition of "natural morphisms" (ie mathematically natural and
Cython implemented) should be prefered to "conversion".
Best,
Vincent
Note: I get some troubles with #13213 which pops out the natural
morphism from QQ to K...
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