[Octave-bug-tracker] [bug #53589] Failing BIST test in bicg

[Rik]

Update of bug #53589 (project octave):

                  Status:         Patch Submitted => Fixed                  
             Open/Closed:                    Open => Closed                 

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Follow-up Comment #5:

I checked in the cset here
(http://hg.savannah.gnu.org/hgweb/octave/rev/b3ee0179d7b0).  Note that I
changed division statements to use the in-place versions which are faster.


alpha = alpha / prod_qv;
==>
alpha ./= prod_qv;


I also changed the documentation for flag 4 to be in the past tense to match
the other flags.


## @item 4: The algorithm could not continue because intermediate values
## became too small or too large for reliable computation.


For the BIST tests, I note that only one of the conditions for flag 4 is
checked.  It is this one


     if (abs (prod_qv) <= eps * abs (alpha))
       flag = 4;
       break
     endif


It would be nice if there was another BIST test which exercised the second bit
of code which sets flag to 4.


    beta = s0' * prec_r0;
    if (abs (prod_rs) <= abs (beta))
      flag = 4;
      break;
    endif


Nevertheless, marking as fixed and closing report.

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