Finite difference method for second order ode

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Oluwaseun Adisa 2021-5-16

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/831303-finite-difference-method-for-second-order-ode

评论： Jan 2021-5-16

Hi. I am trying to solve nonlinear equation using fsolve and repeat graph bet four times with different value. Here is my code:

Function main n = 10 r0 = ones(n, 1) For bet = 0.1:0.1:0.4 Sol = solve(@(r)fun(r, n), r0) norm(fun(sol, n)) end r = ((1:n)-1)/(n-1) Plot(r, sol(0.4,:),'g-*',sol(0.3,:),'m-*',sol(0.2,:),'b-*',sol(0.1,:),'r-*') end

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Oluwaseun Adisa 2021-5-16

using fsolve. Here is my code: Function main n = 10 r0 = ones(n, 1) Sol = solve(@(r)fun(r, n), r0) norm(fun(sol, n)) r = ((1:n)-1)/(n-1) Plot(r, sol(1:n)) end

Outcome >> main Solver stopped prematurely Fsolve stopped because it exceeded the function evaluation limit, options.MaxFunEvals = 1000(the default value).

Jan 2021-5-16

I've mentioned it already: Your code would not run at all, but stop due to the uppercase "Function" immediately.

Please post code in a readable format with one command per line.

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Answer 1

Jan 2021-5-16

0
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/831303-finite-difference-method-for-second-order-ode#answer_700888

编辑：Jan 2021-5-16

在 MATLAB Online 中打开

Matlab is case sensitive. There are no "Function", "For" and "Plot" commands. You should ge corresponding error messages.

I try t guess, how your code should be formatted:

function main
n = 10;
r0 = ones(n, 1);
for bet = 0.1:0.1:0.4
    sol = solve(@(r) fun(r, n), r0);
    norm(fun(sol, n))
end
r = ((1:n)-1) / (n-1);
plot(r, sol(0.4,:), 'g-*', sol(0.3,:), ...
    'm-*', sol(0.2,:), 'b-*',sol(0.1,:), 'r-*');
end
end

There is an unmatched end. The loop over "bet" is useless, because the results are overwritten. It is not clear to me, what you want to achieve, so I cannot fix further errors.