vectorizing solution using fzero

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Pappu Murthy 2017-10-5

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https://ww2.mathworks.cn/matlabcentral/answers/359834-vectorizing-solution-using-fzero

编辑： Matt J 2017-10-5

i have equations of the form f(x,X)=0; where X is a column vector of size N. i can solve using for example

                              f = @(xx) ( f(xx, X))
                              for i = 1:N
                              sol(i) = fzero( f(X(i)), [ 0 , 1000])
                              end

How I would like to eliminate the for loop. Is there a way? I would like something like sol = fzero(f(X), [0,1000]), however it gives an error if I try this. Thanks in advance.

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Answer 1

Matt J 2017-10-5

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编辑：Matt J 2017-10-5

在 MATLAB Online 中打开

Ok. Can I use fsolve to vectorize? My guess based on your answer is that I can not use fsolve either.

You could use fsolve to vectorize, but my feeling is that it is better not to, because this will increase the dimension of the problem and potentially slow convergence.

My recommendation would be to use parfor to parallelize the fzero calls. If the sol(i) are expected to change gradually with i, an alternative way to accelerate things would be to use sol(i-1) as your initial guess, as in,

                              init=[0,1000];
                              for i = 1:N
                               sol(i) = fzero( @(xx) f(xx, X(i)), init);
                                init=sol(i);
                              end