How to vectorize a matrix?

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Sky Scrapper 2019-1-8

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https://ww2.mathworks.cn/matlabcentral/answers/438755-how-to-vectorize-a-matrix

评论： Sky Scrapper 2019-1-14

Dear All,

I have a matrix of 90x12. I need to use 2D look up table for matlab simulink. There i will have to put the vector of input values. That means, Vector for input values x:

[0 1 2 3 4 .........89] and vector for input values 'y': [0 1 2 3 4 5 6 ..11]. How can I write a code that will take the values for x and y automatically with the desired length?

Thanks!

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Fangjun Jiang 2019-1-8

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采纳的回答

OCDER 2019-1-8

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https://ww2.mathworks.cn/matlabcentral/answers/438755-how-to-vectorize-a-matrix#answer_355522

在 MATLAB Online 中打开

%Starting input
M = reshape(1:90*12, 90, 12); %your 90x12 lookup matrix
X = [0 1 3 4 89]; %input X lookup
Y = [0 1 3 5 11]; %input Y lookup
%Matlab does NOT use 0-based index. So add 1.
X = X+1;
Y = Y+1;
%Use sub2ind to to convert (X,Y) to a linear index. 
Idx = sub2ind(size(M), X, Y);
%Collect your value based on index X and Y
Value = M(Idx); 

In short, the above can be simplified as:

M = reshape(1:90*12, 90, 12); %your 90x12 lookup matrix
X = [0 1 3 4 89]; %input X lookup
Y = [0 1 3 5 11]; %input Y lookup
Value = M(sub2ind(size(M), X+1, Y+1));