Opened 7 years ago
Closed 7 years ago
#19256 closed defect (wontfix)
inconsistent numerics with RR/CC/CDF(pi,sqrt(2))
Reported by: | rws | Owned by: | |
---|---|---|---|
Priority: | major | Milestone: | sage-duplicate/invalid/wontfix |
Component: | symbolics | Keywords: | |
Cc: | Merged in: | ||
Authors: | Ralf Stephan | Reviewers: | |
Report Upstream: | N/A | Work issues: | |
Branch: | u/rws/inconsistent_numerics_with_rr_cc_cdf_pi_sqrt_2__ (Commits, GitHub, GitLab) | Commit: | ca2ce549de5caf18a5173253de8b2b78cfe001ba |
Dependencies: | Stopgaps: |
Description (last modified by )
sage: RR(sqrt(2)) 1.41421356237310 sage: CC(sqrt(2)) 1.41421356237309 sage: (CC(pi)-pi).n() -3.10862446895044e-15 sage: (RR(pi)-pi).n() 0.000000000000000 sage: (CC(sqrt(2))-sqrt(2)).n() -5.10702591327572e-15 sage: (RR(sqrt(2))-sqrt(2)).n() 0.000000000000000 sage: (ComplexField(54)(pi)-pi).n() -3.10862446895044e-15 sage: (ComplexField(55)(pi)-pi).n() 0.000000000000000 sage: (ComplexField(60)(sqrt(2))-sqrt(2)).n() -2.22044604925031e-16 sage: (ComplexField(61)(sqrt(2))-sqrt(2)).n() 0.000000000000000
Change History (9)
comment:1 Changed 7 years ago by
- Description modified (diff)
comment:2 Changed 7 years ago by
- Description modified (diff)
comment:3 Changed 7 years ago by
comment:4 Changed 7 years ago by
- Description modified (diff)
comment:5 Changed 7 years ago by
OK, both RR(sqrt(2))
and CC(sqrt(2))
lead to Pynac calling PyNumber_Power(2.00000000000000,1/2)
but the first returns 1.41...10
and the second 1.41...09
.
EDIT:
sage: RR(2)^(1/2) 1.41421356237310 sage: CC(2)^(1/2) 1.41421356237309
So the reason is because CC.__pow__
uses the generic exp(log(a)*b)
instead of mpfr_pow
as in RR.__pow__
.
comment:6 Changed 7 years ago by
- Branch set to u/rws/inconsistent_numerics_with_rr_cc_cdf_pi_sqrt_2__
comment:7 Changed 7 years ago by
- Commit set to ca2ce549de5caf18a5173253de8b2b78cfe001ba
- Status changed from new to needs_review
Let's see what the patchbot says.
New commits:
ca2ce54 | 19256: inconsistent numerics with RR/CC/CDF(pi,sqrt(2))
|
comment:8 Changed 7 years ago by
- Milestone changed from sage-6.9 to sage-duplicate/invalid/wontfix
- Status changed from needs_review to positive_review
No, this is ridiculous. Can't be fixed.
comment:9 Changed 7 years ago by
- Resolution set to wontfix
- Status changed from positive_review to closed
Note: See
TracTickets for help on using
tickets.
I'm not complaining about the problems with limited precision. I just think they should be consistent between
RR
andCC
.