Solving Nonlinear Integral Equation with Newton Method

In summary, the conversation discusses a non-linear integral equation and the use of the Newton method to solve it numerically. After discretizing and using the quadrature rule, the speaker struggles with determining the weights needed for the Newton procedure. They suggest using the trapezoidal scheme, but mention difficulties with solving for y_i.
  • #1
sara_87
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Homework Statement



If I have a non linear integral equation of the form:

[tex]y(s)+\int^x_0{K(x,s,y(s)}ds=f(x)[/tex]

and i want to find a way to solve this numerically using the Newton method

Homework Equations





The Attempt at a Solution



after discretizing, and using the quadrature rule, i have:

[tex]y(s_i)+\sum^i_{j=0}{w_j K(x_i,s_j,y(s_j)}ds=f(x_i)[/tex]

but i am struggling on knowing what the weights wj should be using the Newton procedure.

Thank you in advance.
 
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  • #2
sorry, it should be
[tex]y_i+\sum^i_{j=0}{w_j K(x_i,x_j,y_j)}=f(x_i)[/tex]
where y_i means y(x_i)
I can use the trapezoidal scheme and then i have:
[tex]y_i=f(x_i)-\frac{h}{2}(K(x_i,x_0,y_0))+h\sum^{i-1}_{j=1}{K(x_i,x_j,y_j)}+\frac{h}{2}K(x_i,x_i,y_i)[/tex]

but how can this be solved when i need to know y_i to get y_i since y_i is in the last term of the right hand side?
since i can't make y_i as the subject.
 

What is a nonlinear integral equation?

A nonlinear integral equation is an equation that involves an unknown function in both the integral and non-integral terms. This makes it more complex to solve compared to linear integral equations.

What is the Newton method?

The Newton method, also known as the Newton-Raphson method, is an iterative numerical method used to find the roots of a nonlinear equation. It involves approximating the function with a tangent line at a chosen starting point and then iteratively improving the approximation until a desired level of accuracy is reached.

Can the Newton method be used to solve nonlinear integral equations?

Yes, the Newton method can be used to solve nonlinear integral equations. However, it requires the integral equation to be rewritten as a system of nonlinear algebraic equations, which can then be solved using the Newton method.

What are the advantages of using the Newton method to solve nonlinear integral equations?

The Newton method is a fast and efficient method for finding the roots of nonlinear equations. It also has good convergence properties, meaning that it can find accurate solutions even with a relatively small number of iterations.

Are there any limitations to using the Newton method for solving nonlinear integral equations?

One limitation of the Newton method is that it may fail to converge if the starting point is too far from the actual root. Additionally, the method may also fail if the function is not differentiable or if the Jacobian matrix is ill-conditioned.

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