how to multiply matrix 2 * 2 if the elements of the matrix are row vectors.

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Ed 2013-7-15

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关闭： MATLAB Answer Bot 2021-8-20

fre=100:100:1000;
A=[1 9; 9 5]; % matrix 2*2
B=[1 0; cos(2.*pi.*fre) 0]; %matrix 2*2
C=A.*B;    % ?? how ?? or 
%C=A*B;      % ???
% i need know who the elements of C
disp(C);

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Answer 1

Honglei Chen 2013-7-15

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https://ww2.mathworks.cn/matlabcentral/answers/82145-how-to-multiply-matrix-2-2-if-the-elements-of-the-matrix-are-row-vectors#answer_91849

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B=[1 0; cos(2.*pi.*fre) 0];

will error out since it is not a 2x2 matrix. You will have to use a cell because fre is a vector. You may need to do it with cell arrays if this is what you want

a = rand(2)
b = {1 2;[3 5] 4}
c = cellfun(...
    @times,b,arrayfun(@(x)x,a,'UniformOutput',false),'UniformOutput',false)

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Answer 2

Andrei Bobrov 2013-7-16

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https://ww2.mathworks.cn/matlabcentral/answers/82145-how-to-multiply-matrix-2-2-if-the-elements-of-the-matrix-are-row-vectors#answer_91865

在 MATLAB Online 中打开

fre=100:100:1000;
b = [1 0;0 0];
B = repmat(b,1,1,numel(fre));
B(2,1,:) = cos(2.*pi.*fre);
A=[1 9; 9 5];
C1 = bsxfun(@times,A,B);                                 % times
C2 = reshape(A*reshape(B,2,[]),size(A,1),size(A,2),[]);  % mtimes