"Inner matrix dimensions must agree." i need to multiply two matrices but when i try to multiply them i gave that error, when i try element-wise multiplication i gave no error and also i have to see 804 elements for both layer_a,layer_b.but i see 201

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eren baris alici 2018-3-31

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评论： Walter Roberson 2018-3-31

I want to create a function that has four elements and is square matrice. I also want to create another one which has 4 elements and is square matrice. Then i'll combine this bunch of matrices and finally get overall transfer matrices.

Do you have suggestion about it? im new on matlab. here is my code. entity portion is an issue.

       function [m11_a,m12_a,m21_a,m22_a] = layer_a(delta_za,f);
          delta_za=450e-9;
          N_a=2.5;
          f=3e14:1e12:5e14;
          w=2*pi*f;
          k=N_a*(w/3e8);
          q_a=-k/(2*pi*f*4*pi*10e-7);
          m11_a=cos(k*delta_za);m12_a=(i/q_a)*sin(k*delta_za);
          m21_a=(i*q_a)*sin(k*delta_za);;m22_a=cos(k*delta_za);
       end
       function [m11_b,m12_b,m21_b,m22_b] = layer_b(delta_zb,f);
          delta_zb=400e-9;
          N_b=1.5;
          f=3e14:1e12:5e14;
          w=2*pi*f;
          k=N_b*(w/3e8);
          q_b=-k/(2*pi*f*4*pi*10e-7);
          m11_b=cos(k*delta_zb);m12_b=(i/q_b)*sin(k*delta_zb);
          m22_b=(i*q_b)*sin(k*delta_zb);;m22_b=cos(k*delta_zb);
       end
%top_entity part
[m11_a,m12_a,m21_a,m22_a] = layer_a();
matrice_a=[m11_a m12_a;m21_a m22_a];
[m11_b,m12_b,m21_b,m22_b] = layer_b();
matrice_b=[m11_b m12_b;m21_b m22_b];

thanks..

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Answer 1

Walter Roberson 2018-3-31

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/391878-inner-matrix-dimensions-must-agree-i-need-to-multiply-two-matrices-but-when-i-try-to-multiply-the#answer_312911

在 MATLAB Online 中打开

You have

m2_b=(i*q_b)*sin(k*delta_zb);;m22_b=cos(k*delta_zb);

which is not an assignment to m21_b

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eren baris alici 2018-3-31

Thank you a lot. I’ll try it tomorrow. So i’ll see 804 elements i guess. I need to combine layers and it means i must multiply these matrices. Is it element by element multiplication?

Walter Roberson 2018-3-31

Transfer matrices appear to be typically square matrices except possibly for the last of them. You would typically use algebraic matrix multiplication with them, the * operator, instead of the element-by-element multiplication.

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