Finite difference method solving boundary condition
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Hi try to solve the nonlinear ordinary difference equation by finite difference method with boundary conditions: U(-1) = 0, U(1)=0. The code below.
Function [r, sol] =res(U)
n = 10;
r = ((1:n)-1)/(n-1);
r0=zeros(n+1,1);
color={'r','m','c','b');
For delta = 2:5
Sol = solve(@(r)fun(r, n), r0);
norm(fun(sol, n));
Plot(r, sol(1:n), color{delta-1});hold on;
end
legend('delta=2', 'delta=3','delta=4','delta=5');
Function res=fun(z, n)
lambda =0.1;
beta = 0.1;
eps = 0.1;
m=0;
r = ((1:n)-1)/(n-1);
h=1/(n-1);
U = z(1:n);
res_U = zeros(n, 1);
res_U(1)=0;
For i=2:n-1
res_U(i)=((1+beta*U(i))/h^2)*(U(i+1)-2*U(i)+U(i-1))+((1+beta*U(i))/(r*h))*(U(i+1)-U(i-1))+beta*((U(i+1)-U(i-1))/h)^2+lambda*((1+eps*U(i))^m)*exp(U(i)/(1+eps*U(i)))-delta*U(i);
end
res_U(n)=0;
res = res_U;
end
Outcome
>> res
Warning: Trust-region-dogleg algorithm of Fsolve can not handle non-square systems; using levenberg-marquardt algorithm instead.
Equation solved. Fsolve completed because the vector of function values is near zero as measured by the default value of the function tolerance, and the problem appears regular as measured by the gradient.
'Please help me correct this errors'
5 comentarios
Oluwaseun Adisa
el 22 de Mayo de 2021
Oluwaseun Adisa
el 28 de Mayo de 2021
Torsten
el 28 de Mayo de 2021
Is it necessary to write your own code ? If not, you should use sophisticated matlab code especially designed for this problem class, i.e. bvp4c in your case.
Oluwaseun Adisa
el 5 de Jun. de 2021
Respuestas (0)
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