Ticket #1154 (closed defect: duplicate)

Opened 6 years ago

Last modified 5 years ago

lost precision in RQDF -> RealField conversion

Reported by: zimmerma Owned by: jkantor
Priority: major Milestone: sage-2.8.15
Component: numerical Keywords:
Cc: Work issues:
Report Upstream: Reviewers:
Authors: Merged in:
Dependencies: Stopgaps:

Description 

sage: R = RealField(206)
sage: a = R(5292635226105886036954352397762172773270339156347702272822435/2^205)
sage: b = RQDF(a)
sage: c = R(b)
self= 0.102925468350634334254648605229306925849343943655945448198193123
sage: a - c
1.215432671457254239676575010503930515740283626703352955683812e-63

I checked with b.get_doubles() that b == a, but was unable to find the routine which performs the conversion from b (RQDF) to c (RealField?). It seems R._set_from_qd is not used.

Change History

comment:1 Changed 6 years ago by mabshoff

  • Milestone set to sage-2.8.13

comment:2 Changed 5 years ago by cwitty

  • Status changed from new to closed
  • Resolution set to duplicate

This is one of the issues that's covered by the patch at #1162.

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