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[Octave-bug-tracker] [bug #57603] quadv gives wrong results integrating
From: |
Rik |
Subject: |
[Octave-bug-tracker] [bug #57603] quadv gives wrong results integrating sin^2 or cos^2 on multiple of 8 periods |
Date: |
Wed, 15 Jan 2020 13:06:54 -0500 (EST) |
User-agent: |
Mozilla/5.0 (Windows NT 10.0; WOW64; Trident/7.0; rv:11.0) like Gecko |
Follow-up Comment #3, bug #57603 (project octave):
Check the Octave manual for guidance about which integrands are appropriate
for which numerical integration function. Quoting
The best quadrature algorithm to use depends on the integrand. If you have
empirical data, rather than a function, the choice is trapz or cumtrapz. If
you are uncertain about the characteristics of the integrand, quadcc will be
the most robust as it can handle discontinuities, singularities, oscillatory
functions, and infinite intervals. When the integrand is smooth quadgk may be
the fastest of the algorithms.
Function
Characteristics
quad
Low accuracy with nonsmooth integrands
quadv
Medium accuracy with smooth integrands
quadl
Medium accuracy with smooth integrands. Slower than quadgk.
quadgk
Medium accuracy (1e-6 – 1e-9) with smooth integrands.
Handles oscillatory functions and infinite bounds
quadcc
Low to High accuracy with nonsmooth/smooth integrands
Handles oscillatory functions, singularities, and infinite bounds
For an oscillatory integrand the programmer should be using quadcc, or maybe
quadgk.
However, I do agree that quadv can probably be improved. All of the other
integration routines seem to be able to handle the integrand and bounds
mentioned. There must be something quite specific about quadv that is
preventing it from reaching the correct result.
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- [Octave-bug-tracker] [bug #57603] quadv gives wrong results integrating sin^2 or cos^2 on multiple of 8 periods, anonymous, 2020/01/15
- [Octave-bug-tracker] [bug #57603] quadv gives wrong results integrating sin^2 or cos^2 on multiple of 8 periods, Kai Torben Ohlhus, 2020/01/15
- [Octave-bug-tracker] [bug #57603] quadv gives wrong results integrating sin^2 or cos^2 on multiple of 8 periods, Kai Torben Ohlhus, 2020/01/15
- [Octave-bug-tracker] [bug #57603] quadv gives wrong results integrating sin^2 or cos^2 on multiple of 8 periods,
Rik <=
- [Octave-bug-tracker] [bug #57603] quadv gives wrong results integrating sin^2 or cos^2 on multiple of 8 periods, Olivier Amoignon, 2020/01/16
- [Octave-bug-tracker] [bug #57603] quadv gives wrong results integrating sin^2 or cos^2 on multiple of 8 periods, Olivier Amoignon, 2020/01/16
- [Octave-bug-tracker] [bug #57603] quadv gives wrong results integrating sin^2 or cos^2 on multiple of 8 periods, Rik, 2020/01/16
- [Octave-bug-tracker] [bug #57603] quadv gives wrong results integrating sin^2 or cos^2 on multiple of 8 periods, Rik, 2020/01/17
- [Octave-bug-tracker] [bug #57603] quadv gives wrong results integrating sin^2 or cos^2 on multiple of 8 periods, Kai Torben Ohlhus, 2020/01/21