[Octave-bug-tracker] [bug #37613] Octave precision/accuracy is much lower for quadgk

[Lachlan Andrew]

Update of bug #37613 (project octave):

             Assigned to:                dbateman => caliari                
                 Release:                   3.4.3 => dev                    

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Follow-up Comment #22:

Some trivial feedback on the patch:

* The new assert in the BIST is much longer than 80 characters.  Could it
rewritten to fit under 79 characters?  Perhaps defining


f = @(x) x x .^ 5 .* exp (-x) .* sin (x)


would help.

* Is it worth retaining the comment "Shampine suggests 100*eps"?

* The code


+  if (any (abs (diff (x, [], 2) ./ max (abs (x), [], 2))) < 100 * eps)
+    tooclose = true;
+    return;
+  else
+    tooclose = false;
+  endif


hides the fact that this is an early return.  How about


  if (any (abs (diff (x, [], 2) ./ max (abs (x), [], 2))) < 100 * eps)
    tooclose = true;
    return;
  endif

  tooclose = false;


* Should "tooclose" be "too_close"?

* I don't like shadowing the function  eps  by a variable.  I know that was in
the existing code, but it is also done in the new  __quadgk_eval__.  How about
calling it eps1, since it is eps (1)?


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