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[Octave-bug-tracker] [bug #33792] quadl fails for large integeration tol

From: Marco Caliari
Subject: [Octave-bug-tracker] [bug #33792] quadl fails for large integeration tolerances
Date: Mon, 01 Aug 2011 14:44:59 +0000
User-agent: Mozilla/5.0 (X11; U; Linux i686; en-GB; rv: Gecko/20101203 Firefox/3.6.13

Follow-up Comment #4, bug #33792 (project octave):

Dear Ben,

Matlab passes because it uses the *absolute* tolerance, whereas Octave the
relative. If you try

>> quadl(@(x) sin (2 + 3*x).^2, 0, 10, 0.3 * 7.6082)

where 7.6082 is the (quite bad) value used by Octave as magnitude estimate,
you get the same result 8.1963 in Matlab. In the Matlab help, it is written
that "QUAD may be most efficient for low accuracies": may we also add such a
warning in the help?

Now, among the four quadrature formulas quad, quadl, quadgk and quadcc there
are four different default values for the tolerances and three types of
absolute/relative choices of the tolerance. Isn't it confusing?

Best regards,



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