using meshgrid data in a matrix

Question

mohammad mortezaie 2020-5-29

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链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/537239-using-meshgrid-data-in-a-matrix

评论： mohammad mortezaie 2020-5-29

I tried to use a meshgrid data in a matrix and then evalute eigenvalues. but i faced to "Dimensions of arrays being concatenated are not consistent." error can simeone help me?

my code is:

iform=complex(0.0,1.0);
g_k=2.*t1_tilda.*exp(-iform.*k_x.*a1x).*cos(k_y.*b/2)+t2_tilda.*exp(iform.*k_x.*a2x)+2.*t3_tilda.*exp(iform.*k_x.*a3x).*cos(k_y.*b/2)+t5_tilda.*exp(-iform.*k_x.*a5x);
f_k=4.*t4_tilda.*cos(k_x.*a/2).*cos(k_y.*b/2);
eps1=0:0.01:2;
eps2=0:0.01:2;
[e1,e2]=meshgrid(eps1,eps2);
H=[f_k+e1 g_k;conj(g_k) f_k+e1];
E=eig(H);
landa2=E(1);
landa1=E(2);
EG=landa2-landa1;
contour(e1,e2,EG,10000)

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KSSV 2020-5-29

All the values are not given...show us the complete code.

mohammad mortezaie 2020-5-29

在 MATLAB Online 中打开

this is complete code

iform=complex(0.0,1.0);
t1=-1.22;
t2=3.665;
t3=-0.205;
t4=-0.105;
t5=-0.055;
alpha1x=0.4460;
alpha2x=0.0992;
alpha3x=0.7505;
alpha4x=0.3976;
alpha5x=0.7530;
alpha1y=0.5571;
alpha2y=0.0;
alpha3y=0.2461;
alpha4y=0.2280;
alpha5y=0.0;
alpha1z=0.0;
alpha2z=0.9052;
alpha3z=0.0;
alpha4z=0.3722;
alpha5z=0.2538;
b=3.37;                                                                 
a1x=1.41763;
a2x=0.79732;
a3x=a1x+2*a2x;
a4x=a1x+a2x;
a5x=2*a1x+a2x;
a=2*(a1x+a2x);
k_x=0;
k_y=0;
epsilon_x=0;
epsilon_y=0;
epsilon_z=0;
t1_tilda=t1*(1-2*(alpha1x*epsilon_x+alpha1y*epsilon_y+alpha1z*epsilon_z));
t2_tilda=t2*(1-2*(alpha2x*epsilon_x+alpha2y*epsilon_y+alpha2z*epsilon_z));
t3_tilda=t3*(1-2*(alpha3x*epsilon_x+alpha3y*epsilon_y+alpha3z*epsilon_z));
t4_tilda=t4*(1-2*(alpha4x*epsilon_x+alpha4y*epsilon_y+alpha4z*epsilon_z));
t5_tilda=t5*(1-2*(alpha5x*epsilon_x+alpha5y*epsilon_y+alpha5z*epsilon_z));
g_k=2.*t1_tilda.*exp(-iform.*k_x.*a1x).*cos(k_y.*b/2)+t2_tilda.*exp(iform.*k_x.*a2x)+2.*t3_tilda.*exp(iform.*k_x.*a3x).*cos(k_y.*b/2)+t5_tilda.*exp(-iform.*k_x.*a5x);
f_k=4.*t4_tilda.*cos(k_x.*a/2).*cos(k_y.*b/2);
[m,n] = size(f_k) ; 
eps1 = linspace(0,2,n) ; 
eps2 = linspace(0,2,m) ; 
[e1,e2] = meshgrid(eps1,eps2) ; 
H=[f_k+e1 g_k;conj(g_k) f_k+e2];
E=eig(H);
landa1=E(1);
landa2=E(2);
EG=landa2-landa1;
contour(e1,e2,EG,100)

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Answer 1

KSSV 2020-5-29

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/537239-using-meshgrid-data-in-a-matrix#answer_442087

在 MATLAB Online 中打开

YOu should modify these lines:

eps1=0:0.01:2;
eps2=0:0.01:2;
[e1,e2]=meshgrid(eps1,eps2);

I hope that g_k, f_k are of same dimensions.

[m,n] = size(f_k) ; 
eps1 = linspace(0,2,n) ; 
eps2 = linspace(0,2,m) ; 
[e1,e2] = meshgrid(eps1,eps2) ; 

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KSSV 2020-5-29

EG are Eigen values..it will be an array. You cannot use it to plot contour lines. To plot contour lines EG should be a matrix. You can try using diag(EG). But what exactly you want?

mohammad mortezaie 2020-5-29

My problem exactly is using meshgrid data's e1 and e2 in H matrix. I tried this code without puting e1 and e2 in matrix and code runes without error. So only question here is that how can i use this meshgrids in a matrix and dont face with error.

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