Approximate Integration (Estimating Error)

In summary, the conversation discusses finding an approximation for a given integral using trapezoidal and midpoint formulas. The question of estimating the error is raised, and it is mentioned that the error can be determined by taking the derivative twice. However, the individual is unsure of how to apply this in their specific situation.
  • #1
SciGuy26
5
0

Homework Statement


Found the approximation using Trapezoidal and Midpoint Formulas using 8 rectangles.
How do I estimate the error?

Homework Equations


[tex]\int^{1}_{0}[/tex] cos(x^2)dx


The Attempt at a Solution


Completely confused. I at first tried u-sub but later realized the error was far too great for my integration to be correct. Trig Identity is a no go here either.
I see in the text it wants be to take the derivative twice in order to use a formula to determine the upper bound or lower bound error...Should I differentiate? Ugh..too many questions. Please help
 
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  • #2
. Trapezoidal Approximation: \frac{h}{2}[f(x_0)+2f(x_1)+2f(x_2)+...+2f(x_7)+f(x_8)]where h is the width of a single rectangle and x_i is the ith point in the interval [0,1]Midpoint Approximation:h\sum_{i=1}^{8}f(x_i)where h is the width of a single rectangle and x_i is the midpoint of the ith rectangle. Error: I am completely lost here. I believe I am supposed to differentiate twice but I am not sure how that applies here.
 

1. What is approximate integration?

Approximate integration, also known as numerical integration, is a method used to estimate the value of a definite integral using numerical techniques rather than exact mathematical formulas. This is often necessary when the integral cannot be solved analytically.

2. How is error estimated in approximate integration?

The error in approximate integration is estimated by comparing the numerical solution to the actual value of the integral. This is done by calculating the difference between the two and determining the maximum error or the average error of the approximation.

3. What are the different methods of approximate integration?

Some common methods of approximate integration include the trapezoidal rule, Simpson's rule, and the midpoint rule. These methods are based on dividing the area under the curve into smaller subintervals and using different mathematical formulas to approximate the integral.

4. How accurate is approximate integration?

The accuracy of approximate integration depends on the specific method used and the number of subintervals used. Generally, the more subintervals used, the more accurate the approximation will be. However, it is important to note that even with a large number of subintervals, the approximation will still have some degree of error.

5. In what situations is approximate integration useful?

Approximate integration is useful in situations where the integral cannot be solved exactly or when the function being integrated is too complex to integrate analytically. It is also useful when dealing with large datasets or when a quick estimation of the integral is needed.

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