Need help plotting this

Question

Amanda Lococo 2018-4-13

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/394754-need-help-plotting-this

评论： Star Strider 2018-4-15

I need help plotting this code so that my plot will look like the discontinuous sine waves (bolded black) in the graph posted below the code (for one unit cell). Right now my plot is showing up blank.

clear all;
format long;
im = sqrt(-1);
CellLength = 1;
ibeta = 1;
%Define materal properties 
CellLength = 1;
layers = 2;
d = [0.4;0.6];
dTotal = d(1,1)+d(2,1);
xc = [0;0.4];
Ef = 12;
pf = 3;
cf = sqrt(Ef/pf);
Em = 1;
pm = 1;
cm = sqrt(Em/pm);
w = 5;
T1 = [cos(.2*w) (1/(6*w))*sin(.2*w); -6*w*sin(.2*w) cos(.2*w)];
T2 = [cos(.6*w) (1/w)*sin(.6*w); -w*sin(.6*w) cos(.6*w)];
T = T2*T1;
Z1 = 6*w;
Z2 = w;
Z = [Z1;Z2];
%Solve eigenvalue problem for k
[V,D] = eig(T);                 %D = eigenvalues, %V = eigenvectors
k1 = log(D(1,1))/(im*dTotal);
k2 = log(D(2,2))/(im*dTotal);
k = [k1;k2];
B1 = [1 1;im*30 -im*30];
B2 = [1 1;im*5 -im*5];
C1a = [1 0;0 1];
C2a = [exp(im*k2*0.4) 0;0 exp(-im*k2*0.4)];
a1 = inv(B1)*V(:,1);
a2 = inv(C2a)*inv(B2)*T1*B1*a1;
for x1 = 0:0.1:0.4
    C1 = @(x1)([exp(im*k1*x1) 0;0 exp(-im*k1*x1)]);
    C1 = C1(x1);
    y1 = @(x1)(B1*C1*a1);
    y1 = y1(x1);
end
for x2 = 0.4:0.1:1
    C2 = @(x2)([exp(im*k2*x2) 0;0 exp(-im*k2*x2)]);
    C2 = C2(x2);
    y2 = @(x2)(B2*C2*a2);
    y2 = y2(x2);
end
plot(x1,real(y1(1,:)))
hold on
plot(x2,real(y2(1,:)))
xlabel('Position, x')
ylabel('Displacement, u')

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Answer 1

Star Strider 2018-4-13

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/394754-need-help-plotting-this#answer_314996

Two related problems are that the ‘y1’ and ‘y2’ functions do not use their arguments in their calculations. (I would also rename them ‘y1f’ and ‘y2f’ to avoid confusion with your ‘y1’ and ‘y2’ vectors.)

What do you want to do in those functions?

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Star Strider 2018-4-13

在 MATLAB Online 中打开

I have no idea what you’re doing. This is a bit more efficient, and produces plots:

ibeta = 1;
%Define materal properties 
CellLength = 1;
layers = 2;
d = [0.4;0.6];
dTotal = d(1,1)+d(2,1);
xc = [0;0.4];
Ef = 12;
pf = 3;
cf = sqrt(Ef/pf);
Em = 1;
pm = 1;
cm = sqrt(Em/pm);
w = 5;
T1 = [cos(.2*w) (1/(6*w))*sin(.2*w); -6*w*sin(.2*w) cos(.2*w)];
T2 = [cos(.6*w) (1/w)*sin(.6*w); -w*sin(.6*w) cos(.6*w)];
T = T2*T1;
Z1 = 6*w;
Z2 = w;
Z = [Z1;Z2];
%Solve eigenvalue problem for k
[V,D] = eig(T);                 %D = eigenvalues, %V = eigenvectors
k1 = log(D(1,1))/(1i*dTotal);
k2 = log(D(2,2))/(1i*dTotal);
k = [k1;k2];
B1 = [1 1;1i*30 -1i*30];
B2 = [1 1;1i*5 -1i*5];
C1a = [1 0;0 1];
C2a = [exp(1i*k2*0.4) 0;0 exp(-1i*k2*0.4)];
a1 = B1\V(:,1);
a2 = (B2*C2a)\T1*B1*a1;
x1 = 0:0.1:0.4;
C1 = @(x1)([exp(1i*k1*x1) 0;0 exp(-1i*k1*x1)]);
y1 = zeros(2, numel(x1));
for k = 1:numel(x1)
    y1(:,k) = (B1*C1(x1(k))*a1);
end
x2 = 0.4:0.1:1;
C2 = @(x2)([exp(1i*k2*x2) 0;0 exp(-1i*k2*x2)]);
y2 = zeros(2, numel(x2));
for k = 1:numel(x2)
    y2(:,k) = (B2*C2(x2(k))*a2);
end
plot(x1,real(y1(1,:)))
hold on
plot(x2,real(y2(1,:)))
xlabel('Position, x')
ylabel('Displacement, u')

I can’t completely vectorise this because I’m not certain what you’re doing. I moved the function definitions out of the loops, and called them in the ‘y1’ and ‘y2’ calculations.

You’ll have to determine if the plots are correct. I added preallocations for ‘y1’ and ‘y2’.

Amanda Lococo 2018-4-15

I will try that then! Thanks again for all of your help!

Star Strider 2018-4-15

As always, my pleasure!

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