[Octave-bug-tracker] [bug #31070] fzero cannot compute initial bracketing

[Jaroslav Hajek]

Update of bug #31070 (project octave):

                Severity:              3 - Normal => 1 - Wish               
                Priority:              5 - Normal => 3 - Low                
              Item Group:        Incorrect Result => Feature Request        
             Assigned to:                    None => highegg                

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Follow-up Comment #2:

fzero is designed to work with a bracketing, and it is unrealistic to expect
it to always find one, as well as to expect it to behave identically to
Matlab.
Therefore, I don't see anything "incorrect" about the result.
If a valid bracketing is not given, fzero simply tries a number of trial
points, and in this case none of them works. Of course, for *any* trial
sequence you can construct a failing case. 

I don't object to using a better trial sequence, but please

1: Make it separate from any other changes.
2: Document what exactly the new sequence is and why is it better. It should
be clear from the above that merely pointing out an example where this
sequence works and the existing one doesn't is not enough, you should present
some sort of discussion about common and uncommon use cases.

PS. If you want to change the default tolerance, make it a separate change
with an explanation why.
PPS. Prior to 3.2, fzero didn't exist at all in Octave, so it surely wasn't
giving results more similar to Matlab.

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