Can the Simpsons 3/8 Rule be Extended to Calculate Double Integrals?

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Discussion Overview

The discussion centers on the application of Simpson's 3/8 rule for calculating double integrals, exploring whether this method can be extended from single integrals to double integrals. Participants examine the suitability of various numerical integration techniques for different types of regions and integrands.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants question the characterization of Simpson's 3/8 rule as "optimal" for double integrals, noting its adaptation from single integrals.
  • It is suggested that Simpson's rules and the trapezoidal rule can be adapted for double integrals, particularly for rectangular or triangular regions.
  • One participant proposes that changing variables may be necessary when dealing with non-rectangular regions for double integrals.
  • Another participant indicates that a rectangular region provides the most accurate results with Simpson's rule due to the requirement for evenly spaced ordinates in a 2-D grid.
  • A suggestion is made that 2-D Gaussian quadrature might be more effective for evaluating double integrals over more general shapes.
  • One participant describes a specific case involving a surface integral of a scalar function, asserting that it resembles a double integral over a rectangle, which may allow the use of Simpson's 3/8 rule.

Areas of Agreement / Disagreement

Participants express differing views on the applicability of Simpson's 3/8 rule to double integrals, with some supporting its use under certain conditions while others advocate for alternative methods. The discussion remains unresolved regarding the optimal approach for various types of integrals.

Contextual Notes

Participants highlight limitations related to the shape of the regions being integrated and the need for specific conditions, such as the spacing of ordinates, which may affect the accuracy of the methods discussed.

DivergentSpectrum
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how do i numerically calculate a double integral?
as i understand simpsons 3/8 rule is the optimal method for a single integral, is it still true for double integrals?
if so, how do i extend the 3/8s rule to do a double integral?
 
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DivergentSpectrum said:
how do i numerically calculate a double integral?
as i understand simpsons 3/8 rule is the optimal method for a single integral, is it still true for double integrals?
if so, how do i extend the 3/8s rule to do a double integral?

I don't know what you mean by the Simpson's 3/8 rule being 'optimum'. It uses a different number of ordinates than Simpson's first rule (1-4-1), so that an even number of ordinates can be accommodated easily, where Simpson's first rule takes an odd number of ordinates.

Simpson's rules and the trapezoidal rule can be adapted to evaluate double integrals, and they tend to work well for regions which are triangular or rectangular. For more general regions, other methods may be easier to use for such evaluations; there are no hard and fast rules.

This paper illustrates a typical quadrature based on a 2-D Simpson's Rule:

https://www.math.ohiou.edu/courses/math3600/lecture24.pdf
 
Only with rectangles? so I am guessing id have to be able to do some kind of change of variables then right?
 
DivergentSpectrum said:
Only with rectangles? so I am guessing id have to be able to do some kind of change of variables then right?

Due to the nature of the Simpson's rule setup, a rectangular region will give the most accurate results with the least fuss, because the ordinates must be evenly spaced in a 2-D grid.

If the regions over which you are trying to evaluate a double integral are of a more general shape, perhaps a 2-D Gaussian quadrature method might give you fewer headaches about locating the ordinates in the region where the integrand must be evaluated.
 
what I am doing in this case is i am doing a surface integral of a scalar function
using x(u,v),y(u,v),z(u,v) as the parameterized surface
so because this is of the form ∫∫something dudv where umin umax vmin vmax are all constants so its the same as a double integral over a rectangle and it should work right?
 

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