For loop with three variables

Question

Jacqueline Rigatto 2020-10-31

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/632454-for-loop-with-three-variables

评论： Jacqueline Rigatto 2020-11-1

u= [1.192 1.194 1.120];  % u_* [ms-1]
z=[0.0021 0.0029  0.0033];   % z_0 [m]
T=2:1:16;
f=1./T;
sigma= 2*pi*f; %[s-1]
g=9.8;
K=sigma.^2./g;  %  [m-1]
k=0.4;
i_teta=1:36;
teta_i=10.*i_teta;
for i=1:length(sigma)
    for ii=1:length(K)
        for j=1:length(teta_i)
            mi(i,j)=(((g*z(1,1).*(K(ii).^2))./sigma.^2).*exp((k*sigma)./(K(ii).*u(1,1)).*cos(teta_i)))
        end
    end
end

The loop I want to make is from the equation below, where: u and z are fixed; sigma and k they are in two lines one below the other, both with 15 elements; and theta_i in column with 36 elements.

I am unable to loop for two rows and a column varying. How can I do (my code is above)?

I thank you for your help

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Answer 1

Alan Stevens 2020-10-31

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https://ww2.mathworks.cn/matlabcentral/answers/632454-for-loop-with-three-variables#answer_530184

编辑：Alan Stevens 2020-10-31

在 MATLAB Online 中打开

1.You could have m as a function of, i, j and ii. Your loop then might look like

for i=1:length(sigma)
    s = sigma(i);
    for ii=1:length(k)
        K = k(ii);
        for j=1:length(teta_i)
            theta = teta_i(j);
            mi(i,j,ii)=(g*z(1,1).*K.^2./s.^2).*exp(K*s./(K.*u(1,1)).*cos(theta));
        end
    end
end

However, this doesn't look right compared with your mathematical equation because you have confused Kappa and k:

I suspect they are not the same.

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Alan Stevens 2020-10-31

在 MATLAB Online 中打开

Since sigma and K go hand in hand the following should produce mi in the form you want

u= [1.192 1.194 1.120];  % u_* [ms-1]
z=[0.0021 0.0029  0.0033];   % z_0 [m]
T=2:1:16;
f=1./T;
sigma= 2*pi*f; %[s-1]
g=9.8;
K=sigma.^2./g;  %  [m-1]
k=0.4;
i_teta=1:36;
teta_i=10.*i_teta;
mi = zeros(numel(teta_i),numel(sigma));
for i=1:length(sigma)
        
    for j=1:length(teta_i)
        mi(j,i)=(((g*z(1,1).*(K(i).^2))./sigma(i).^2).*exp((k*sigma(i))./(K(i).*u(1,1)).*cos(teta_i(j))));
    end
   
end