Iteration/Root finding algorithm

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In summary, the conversation discusses solving a problem involving a recursive equation and finding the limit of a sequence. The solution for part a) is achieved by factorizing a cubic equation, but the solution for part b) is still unknown. It is mentioned that the sequence must be contractive for it to converge, and the focus is on showing that the limit of the sequence is the only possible solution and how to solve a specific part of part b).
  • #1
Oshada
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Homework Statement



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The Attempt at a Solution



I've managed to do part a), by factorising the cubic you get when you rearrange the terms. I'm mostly stumped for part b). I know the sequence has to be contractive, otherwise it wouldn't converge. Also, how do I show it's the only solution? Thank you very much!
 
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  • #2
I'm not sure what you mean by "show it's the only solution". There are, in fact, three (complex) solutions to the equation. What you are asked to do is show that the limit (which, assuming the sequence converges, is unique) does, in fact, satisfy the given equation, not that it is the "only" solution.

Your recursion equation is [itex]x_{n+1}= 2x_n/3+ \lambda/(3x_n^2)[/itex]. Take the limit of both sides as n goes to infinity and you have [itex]x= 2x/3+ \lambda/3x^2[/itex], where [itex]x= \lim_{n\to\infty} x_n[/itex]. Multiply both sides of that by [itex]3x^2[/itex].
 
  • #3
Sorry, I meant how to show that the only possible value for limn→∞xn is cbrt(λ)! Also, if you could explain how to solve ii) of b) that would be great!
 
  • #4
Bump: Any ideas about b) are welcome.
 

FAQ: Iteration/Root finding algorithm

What is an iteration/root finding algorithm?

An iteration/root finding algorithm is a mathematical procedure used to approximate the solutions of a given equation or system of equations. It involves repeatedly evaluating a function at different input values until a desired level of accuracy is achieved.

How does an iteration algorithm work?

An iteration algorithm starts with an initial guess for the solution and then uses a predetermined formula to update that guess with each iteration. The process continues until the updated guess is close enough to the actual solution, as determined by a specified tolerance level.

What is the difference between an iteration algorithm and a root finding algorithm?

The terms "iteration algorithm" and "root finding algorithm" are often used interchangeably, but there is a subtle difference between the two. While an iteration algorithm uses a specific formula to update the initial guess, a root finding algorithm can use a variety of techniques, such as bisection, Newton's method, or the secant method, to find the solution.

What types of equations can be solved using iteration/root finding algorithms?

Iteration/root finding algorithms can be used to solve a wide range of equations, including polynomial equations, transcendental equations, and systems of equations. They can also be applied to optimization problems, where the goal is to find the maximum or minimum value of a function.

What are the advantages of using iteration/root finding algorithms?

Iteration/root finding algorithms are very versatile and can be applied to a variety of problems. They also have the advantage of being relatively easy to implement and can often provide a solution even when a closed-form solution is not available. Additionally, these algorithms can handle complex equations and systems that may not have a straightforward solution.

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