Opened 10 years ago

Closed 10 years ago

Last modified 10 years ago

#6814 closed defect (invalid)

jordan_form transformation lack of precision sage 4.1.1

Reported by: Henryk.Trappmann Owned by: tbd
Priority: major Milestone: sage-duplicate/invalid/wontfix
Component: linear algebra Keywords: jordan, precision, matrix, transformation
Cc: Merged in:
Authors: Reviewers:
Report Upstream: N/A Work issues:
Branch: Commit:
Dependencies: Stopgaps:

Description

There is an example for a lack of precision exception in the doc of jordan_form

sage: b = matrix(ZZ,3,3,range(9))
sage: jf, p = b.jordan_form(RealField(15), transformation=True)
...
ValueError: cannot compute the transformation matrix due to lack of precision

But if one increases the precision to the maximum still the same error occurs

sage: b = matrix(ZZ,3,3,range(9))
sage: jf, p = b.jordan_form(RealField(16777216), transformation=True)
...
ValueError: cannot compute the transformation matrix due to lack of precision

Change History (3)

comment:1 Changed 10 years ago by AlexGhitza

  • Component changed from algebra to linear algebra

comment:2 Changed 10 years ago by spancratz

  • Report Upstream set to N/A
  • Resolution set to invalid
  • Status changed from new to closed

The error messages come up because the code does not actually detect numerically instability. Instead, it notices when it fails, and assumes the only possible reason for this could be numerical instability. Instead, there's a bug in the actual code.

Thus, this ticket can be closed as being "invalid".

comment:3 Changed 10 years ago by mvngu

  • Milestone changed from sage-4.3.1 to sage-duplicate/invalid/wontfix
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