#15780: Increase Performance in Projective Morphism
-------------------------------------+-------------------------------------
Reporter: drose | Owner: drose
Type: enhancement | Status: needs_work
Priority: minor | Milestone: sage-6.2
Component: algebraic | Resolution:
geometry | Merged in:
Keywords: Projective, | Reviewers: Ben Hutz
Morphism | Work issues:
Authors: Dillon Rose | Commit:
Report Upstream: N/A | 2a4342e2ec2d4d5d3524ab9a7a0aa6510bd66447
Branch: | Stopgaps:
u/drose/ticket/15780 |
Dependencies: #16051, #16168 |
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Comment (by nbruin):
* justify constant `2**27` as bound on "no overflow in float" (you should
use doubles).
* for the sake of defensive programming, would you use
{{{
max(abs(c.lift()) for c in coefficients)
}}}
instead? `max(GF(17)).lift()` happens to work at present, but it doesn't
really make mathematical sense.
Also, if you really want to scrape the bottom on this, you should use
balanced representatives, also on the coordinates when you fill them in.
That would give you a larger range where you can use float.
What you'd really need is a `cdef ulong` domain. Then you could just
evaluate with 64-bit integers, which would give you a much better bound
than `2^27`.
--
Ticket URL: <http://trac.sagemath.org/ticket/15780#comment:29>
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