The Operation of Multiple Ranges in Definite Integration

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Discussion Overview

The discussion revolves around the operation of multiple ranges in definite integration, specifically focusing on the notation and implications of integrating functions with several bounds. Participants explore the interpretation of the notation and how to approach calculations involving multiple integrals.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant questions whether the expression provided is an equation or an iterated integral, seeking clarification on the operation implied by multiple ranges.
  • Another participant asserts that the expression equals some value, N, and relates it to a specific integral form, but does not clarify the notation of the three bars.
  • Some participants explain that the bars represent bounds in integration, with one providing an example of a single integral to illustrate this point.
  • There is uncertainty about how to handle multiple sets of bounds, with one participant asking if the results of each integral should be added together or approached differently.
  • Another participant suggests working through one integral at a time rather than attempting to evaluate all integrals simultaneously.
  • A later reply discusses the order of evaluation in integrals over a rectangular solid, noting that the order does not matter in this case, but may be important in more complex scenarios where limits depend on other variables.

Areas of Agreement / Disagreement

Participants express differing views on how to interpret the notation and approach the calculation of multiple integrals. There is no consensus on the best method for handling the multiple ranges or the implications of the notation.

Contextual Notes

Some participants highlight the potential complexity of integrating functions where the limits of one integral depend on another variable, indicating that this could affect the order of evaluation.

Hypatio
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I have the equation
[tex]G[xy\textup{ln}(z+R)+xz\textup{ln}(y+R)+yz\textup{ln}(x+R)]|^{x_2-x_0}_{x_1-x_0}|^{y_2-y_0}_{y_1-y_0}|^{z_2-z_0}_{z_1-z_0}<br /> [/tex]
My question is what exactly is the operation implied by having multiple ranges (x_2-x_0 to x_1-x_0, y_2-y_0 to y_1-y_0, and z_2-z_0 to z_1-z_0)? Do you perform the difference operation for each range and then add them together?

Edit: Fixed title.
 
Last edited:
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Hypatio said:
I have the equation
[tex]G[xy\textup{ln}(z+R)+xz\textup{ln}(y+R)+yz\textup{ln}(x+R)]|^{x_2-x_0}_{x_1-x_0}|^{y_2-y_0}_{y_1-y_0}|^{z_2-z_0}_{z_1-z_0}[/tex]
First off, this isn't an equation (there's no = in it). Is this supposed to be an iterated integral?
Hypatio said:
My question is what exactly is the operation implied by having multiple ranges (x_2-x_0 to x_1-x_0, y_2-y_0 to y_1-y_0, and z_2-z_0 to z_1-z_0)? Do you perform the difference operation for each range and then add them together?

Edit: Fixed title.
 
Mark44 said:
First off, this isn't an equation (there's no = in it). Is this supposed to be an iterated integral?
It equals some value, N.

It is (part of) the solution to the equation

[tex]N=G\int_{x_1}^{x_2}\int_{y_1}^{y_2}\int_{z_1}^{z_2}\frac{1}{R}dzdydx[/tex]

I just don't understand the notation of the three bars in the solution.
 


They are bounds. For example...

[tex]\int_0^3 x^2 dx = \frac{x^3}{3} |_0^3[/tex]

Does that answer your question?
 


Char. Limit said:
They are bounds. For example...

[tex]\int_0^3 x^2 dx = \frac{x^3}{3} |_0^3[/tex]

Does that answer your question?

I know that they are bounds, but what do I do when there is more than one set of bounds? Do I calculate each of the three and then add them together or something different?
 


I really don't know. I wouldn't work all of the integrals at once, then apply all of the bounds. I would work through one integral at a time.
 
[tex]f(x,y, z)\left|_{x= a}^b\left|_{y= c}^d\left|_{z= e}^f= f(b, y, z)- f(a, y, z)\left|_{y= c}^dleft|_{z= e}^f[/tex]
[tex]= f(b, d, z)- f(a, c, z)- (f(b, d, z)- f(b, c, z))\left|_{z= e}^f= f(b, d, z)+ f(b, c, z)- f(a, c, z)- f(b, d, z))\left|_{z= e}^f[/tex]
[tex]= f(b, d, z)+ f(a, c, f)+ f(a, d, f)+ f(a, c, f)- (f(a, d, f)+ f(a, c, f)+ f(b, d, e)+ f(b, c, f))[/tex]

In other words, it doesn't matter in which order you evaluate x, y, or z.

(This is integrating over a rectangular solid. In more general cases, where the limits on one integral will depend on another variable, of course, the order is important.)
 
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