How to calculate values at the nodal points?

Question

revathy M 2017-9-27

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/358618-how-to-calculate-values-at-the-nodal-points

回答： AM 2020-3-26

hi!

Need to evaluate certain values at every nodal point. Have discretized then have used for loop to do calculation. Not getting any error but there is a variation in the result. My need is the value of P1,P2 ..... etc must be evaluated at each point. Do x_bar(j) represent the value of x_bar at the j th position (like x_bar(1)=0,x_bar(1)=0.01etc).

Xb = [0, .5, 1.25, 1.50];
delx_bar = [.01, .005, .0001];
x_bar = cumsum([Xb(1), repelem(delx_bar,diff(Xb)./delx_bar)]);
del_eta=0.02;
eta_inf=4;
n_xbar=length(x_bar);
eta=(0:del_eta:eta_inf).';
n_eta=length(eta);
for j=2:n_xbar-1
 for i=2:n_eta
P1(j) = 1 - cos(x_bar(j));
P2(j) = 1 + cos(x_bar(j));
 end
end

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Walter Roberson 2017-9-27

What is the purpose of your "for i=2:n_eta" loop? You do not use "i" inside the loop.

revathy M 2017-9-30

Have just given the part of the code.i runs over the row and j runs over the column.

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Answer 1

KSSV 2017-9-28

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/358618-how-to-calculate-values-at-the-nodal-points#answer_283451

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Xb = [0, .5, 1.25, 1.50];
delx_bar = [.01, .005, .0001];
x_bar = cumsum([Xb(1), repelem(delx_bar,diff(Xb)./delx_bar)]);
del_eta=0.02;
eta_inf=4;
n_xbar=length(x_bar);
eta=(0:del_eta:eta_inf).';
n_eta=length(eta);
P1 = zeros([],[]) ;
P2 = zeros([],[]) ;
for j=2:n_xbar-1
    for i=2:n_eta
        P1(i,j) = 1 - cos(x_bar(j));
        P2(i,j) = 1 + cos(x_bar(j));
    end
end