Code for boundary value problem

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Ollie 2015-10-12

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https://ww2.mathworks.cn/matlabcentral/answers/248193-code-for-boundary-value-problem

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I'm trying to answer this question:

This is the code I have produced:

    function [x,y] = bvp(coeff, bcs, xspan, h)
    N = (xspan(2)-xspan(1))/(h); 
    x = xspan(1):h:xspan(2);
    main = [ones(N-1,1).*(coeff(3)*h^2-2*coeff(1))];
    sub = ones(N-2,1).*(coeff(1)-coeff(2)*h/2);
    super = ones(N-2,1).*(coeff(1)+coeff(2)*h/2); 
    A = (diag(main) + diag(sub,-1) + diag(super,1));
    B = [(-(coeff(1)-coeff(2)*h/2)*bcs(1));zeros(N-3,1);-(coeff(1)+coeff(2)*h/2)*bcs(2)];
    y = A\B;
    y = [bcs(1); y; bcs(2)];
end