creating for loop in fzero

Question

fartash2020 2017-11-12

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/366578-creating-for-loop-in-fzero

评论： Star Strider 2017-11-28

Dear all, I want to plot "z" vs. "kappa" where kappa is changing from 1 to 0. this is my @ff function:

function y = f(x)
y = (1/pi)*((0.1*x)-(((sqrt((1+x)./2)).*exp(1).^-(6*(sqrt(2*0.1*(1+x))))))*(kappa*(sqrt((1-x)/(1+x)))-(sqrt((1+x)/(1-x)))));

after that using fzero I want to find "z" for every single kappa in the region in order to get the plotted data:

fun = @ff; % function
x0 = 0; % initial interval
z = fzero(fun,x0);

now how can I create a loop to change kappa from 1 to 0 and get "z" for each of them on my plot. many Thanks in Advance,

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Answer 1

Star Strider 2017-11-12

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/366578-creating-for-loop-in-fzero#answer_290676

在 MATLAB Online 中打开

Try this:

f = @(x,kappa) (1/pi)*((0.1*x)-(((sqrt((1+x)./2)).*exp(-(6*(sqrt(2*0.1*(1+x))))))).*(kappa*(sqrt((1-x)./(1+x)))-(sqrt((1+x)./(1-x)))));
N = 10;                                             % Length Of ‘kappa’ Vector
kappa = linspace(0, 1, N);
for k1 = 1:N
    z(k1) = fzero(@(x) f(x, kappa(k1)), 1E-3);
end
figure(1)
plot(kappa, z)
xlabel('\kappa')
ylabel('z(\kappa)')
grid

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fartash2020 2017-11-28

Thanks Star Strider, but how can I create a nested loop?

Star Strider 2017-11-28

在 MATLAB Online 中打开

Try this:

N = 100;
kd = 6;
kappa = 0.1;
lambda = linspace(0.05,0.25, N);
Delta_E = linspace(0.1,0.35, N);
[Lm,DE] = meshgrid(lambda, Delta_E);
f = @(x,lambda,Delta_E) ((Delta_E)+(lambda*x)-(((sqrt((1+x)./2)).*exp(-(kd*(sqrt(2*lambda*(1+x))))))).*(kappa*(sqrt((1-x)./(1+x)))-(sqrt((1+x)./(1-x)))));
for k1 = 1:length(lambda)
    for k2 = 1:length(Delta_E)
        z(k1,k2) = fzero(@(x) f(x,lambda(k1),Delta_E(k2)), rand);
    end
end
figure(1)
mesh(lambda, Delta_E, z)

You might find it worthwhile to plot the absolute value of ‘z’, because the results are complex when they are not NaN, although the plot itself reveals little.

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