Integral Approximation/Error Analysis

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    Analysis Integral
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Discussion Overview

The discussion revolves around approximating the integral of the function e^(x^2 + 3x + 1) from 0 to 3 using Riemann sums or the trapezoidal rule, with a specified accuracy of within 0.2 of the actual integral value. Participants are exploring the implications of the function's behavior on the required number of subdivisions for accurate approximation.

Discussion Character

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

Main Points Raised

  • One participant expresses difficulty in determining the appropriate number of subdivisions (n) for the approximation, noting that it results in a very large value.
  • Another participant points out that the steep slope of the function at the endpoint (x=3) contributes to the need for a fine mesh in the approximation.
  • A clarification is made regarding the accuracy requirement, with one participant confirming that the approximation must be within 0.2 of the actual integral.
  • It is noted that since the function is concave up, the trapezoidal rule will always overestimate the integral value, leading to a discussion about the implications of this on the required n value.
  • One participant shares their experience of obtaining n = 61,000, expressing surprise that it was not higher.

Areas of Agreement / Disagreement

Participants generally agree on the challenges posed by the function's steep slope and concavity, but there is no consensus on the best approach or the implications of the large n value required for accurate approximation.

Contextual Notes

Participants have not resolved the assumptions regarding the nature of the accuracy requirement (absolute vs. relative) and how it affects the approximation process. The discussion does not clarify the specific mathematical steps leading to the large n value.

Who May Find This Useful

Individuals interested in numerical methods for integration, particularly those dealing with challenging functions or seeking to understand the implications of function behavior on approximation techniques.

rwsjyiy
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Hi so i have this problem that I am working on but I am having trouble with it.
I have to approximate the integral using either Riemann Sum or Trapezoidal sum with .2 of the actual integral. It is the integral of e^(x^2+3x+1) from 0 to 3.
Every time i try to find the n value, it ends up being huge! so it gives me a really small delta x number. Any Help?
Thanks
 
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It is not surprising. The exponent is 19 at the end point, so the function is very large and has a steep slope. You need a very fine mesh near x=3. Is the .2 absolute or relative? If absolute, your result (n huge!) is not surprising.
 
it says approximate the integral within.2 and be at least as great as the actual integral
 
f(x) is concave up so the trapezoidal rule always overestimates the value. I was actually surprised that I only got n = 61,000 works lol, thought it would be higher.
 
Last edited:

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