Numerical methods that need a guess/approximate solutions

In summary, the conversation discusses the use of analog computers for solving time-dependent ODE/PDEs, which can be fast but not very accurate. The speaker is curious if there are any numerical methods or solvers that can take an approximate solution and generate a more accurate one. The respondent suggests using least action principles as a possible method and mentions having written code for finding periodic orbits of chaotic systems. The speaker asks for more details on the codes and the respondent inquires about the initial information needed for the process. Another speaker brings up a differential equation they have been trying to solve numerically but have encountered complex numbers. They are looking for a program to estimate complex plots and numbers.
  • #1
Nate_CU
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Hello everyone! I am currently playing with an old analog computer, which could solve time-dependent ODE/PDEs pretty fast, without time-stepping. But the problem with analog computer's solutions is that they are not very accurate. I am very curious that is there any numerical method/solver which can take an approximate solution (over the time domain) to further process it, and generate a more accurate solution??

Thanks in advance!
 
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  • #2
I can't think of any general ones, but applications of the least action principles should be able to search around an approximate solution to find an exact solution more quickly.

I've also written code for searching out periodic orbits of chaotic systems. Having approximations to begin with would make the process faster.
 
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  • #3
Dr. Courtney said:
I can't think of any general ones, but applications of the least action principles should be able to search around an approximate solution to find an exact solution more quickly.

I've also written code for searching out periodic orbits of chaotic systems. Having approximations to begin with would make the process faster.
Dear Dr. Courtney,

Thanks for your reply! I have never heard of "least action principles" numerical solvers for solving ODEs. (Sorry about my weak math background!) Is this a popular way to solve ODEs?

Analog computers can also provide solutions of ODEs describing chaotic systems. Can you provide me more details on your codes? What initial information do you need to get started? Thank you!
 
  • #4
hello every one
i have a differential equation:
Y''(x)+A*y(x)*(1+B*(y(x)^0.687))=0
i solve it numerically but i need a function for it unfortunately its give me complex number.
i need some program that can estimate complex plot and number
thank you
 

1. What are numerical methods that require a guess or approximate solution?

Some common numerical methods that require a guess or approximate solution include the bisection method, Newton's method, and the secant method.

2. Why do these methods need a guess or approximate solution?

These methods rely on iteration to approach the true solution, so an initial guess is needed to start the process. Without a starting point, the methods would not be able to converge to the correct solution.

3. How accurate are the solutions obtained from these methods?

The accuracy of the solutions obtained from numerical methods that require a guess or approximate solution depends on the initial guess and the number of iterations performed. With a good initial guess and enough iterations, the solutions can be very accurate.

4. Can these methods be used for any type of problem?

No, these methods are typically used for solving equations that cannot be solved analytically, such as transcendental equations or systems of nonlinear equations. They may not be suitable for all types of problems and may require modification for specific cases.

5. How do I know which numerical method to use for a given problem?

The choice of numerical method depends on the specific problem and the structure of the equation. It is important to consider factors such as the availability of initial guesses, the convergence rate of the method, and the complexity of the problem before selecting a method.

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