[Octave-bug-tracker] [bug #65182] [octave forge] (image) "test stretchlim" fails

[Dmitri A. Sergatskov]

URL:
  <https://savannah.gnu.org/bugs/?65182>

                 Summary: [octave forge] (image) "test stretchlim" fails
                   Group: GNU Octave
               Submitter: dasergatskov
               Submitted: Fri 19 Jan 2024 07:07:22 PM UTC
                Category: Octave Forge Package
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Unexpected Error or Warning
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
                 Release: 9.0.90
         Discussion Lock: Any
        Operating System: GNU/Linux
           Fixed Release: None
         Planned Release: None


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Follow-up Comments:


-------------------------------------------------------
Date: Fri 19 Jan 2024 07:07:22 PM UTC By: Dmitri A. Sergatskov <dasergatskov>
"test stretchlim" on octave 9.0.1 (compiled with AVX).

octave:18> test stretchlim
***** test
 assert (stretchlim ([(.05:.05:1) (2:4)], 0.2), [0.25; 0.95], eps)
 assert (stretchlim ([(.05:.05:1) (2:5)], 0.2), [0.25; 1])
 assert (stretchlim ([(.05:.05:1) (2:6)], 0.2), [0.3; 1])
 assert (stretchlim ([(.05:.05:1) (2:7)], 0.2), [0.3; 1])
!!!!! test failed
ASSERT errors for:  assert (stretchlim ([(.05:.05:1), (2:6)], 0.2),[0.3; 1])

  Location  |  Observed  |  Expected  |  Reason
    (1)          0.3          0.3        Abs err 5.5511e-17 exceeds tol 0 by
6e-17
octave:19> format bit
octave:20> 0.3
ans = 0011111111010011001100110011001100110011001100110011001100110011
octave:21> stretchlim ([(.05:.05:1), (2:6)], 0.2)
ans =

  0011111111010011001100110011001100110011001100110011001100110100
  0011111111110000000000000000000000000000000000000000000000000000

octave:22> stretchlim ([(.05:.05:1), (2:7)], 0.2)
ans =

  0011111111010011001100110011001100110011001100110011001100110100
  0011111111110000000000000000000000000000000000000000000000000000



This "fraction-of-EPS" roundoff error seems typical when AVX instructions are
in use. 
perhaps the function is OK and the test precision just needs to be relaxed by
EPS.

Sincerely,
Dmitri.
-- 








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