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I programmed a Nystrom Algorithm specifically for my problem:

This is the exact equation i want to solve:

$y′′=(w2−e∗cos(t))∗sin(t)−b∗y′$

And this is my algorithm

function [T U] = Nystrom(a,b,u0,h,w,v,e) % a is the initial value % b is the final value % u0 is a vector with the initial conditions y(0) and y'(0) % h is the size of every step % w, v and e are constants.  M=(b-a)/h+2; %Steps T=zeros(1,M+2); %Time vectors U=zeros(2,M+2); %y and y' vector T=a:h:b; % i use uniform steps of size h U(:,1)=u0; %i stablish the initial conditions  U(1,2)=U(1,1)+h*U(2,1)+(h^2)/2 * (w^2-e*cos(T(1))*sin(U(1,1))-v*U(2,1));  for i=3:M     U(1,i)=(-2*U(1,i-1)+U(1,i-2)-h^2*(w^2-e*cos(T(i-1)))*sin(U(1,i-1))-h*v*(U(1,i-2))/2)/(1-h*v/2); end  for i=1:M     U(2,i+1)=(U(1,i+2)-U(1,i))/(2*h); end  U=U'; T=T'; 

The problem is, it doesn't work and i don't know why. It's throwing values bigger and bigger in every step, but solving the same problem with other methods gives different, quite smaller values.

Any idea could help. Thank you!

0 Answers 0