Hello everyone. I would like to ask you two questions. The first problem: know A = [0.4,0.9], B = [2,9], and find the linear equation through A and B. The second problem: how to remove all zeros in a matrix. D=[1 2 3; 1 7 2; 6 2 7,0 0 0,0 0 0].

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Wesley on 1 Jun 2021
Commented: Wesley on 1 Jun 2021
I would like to ask you two questions. The first problem: know A = [0.4,0.9], B = [2,9], and find the linear equation through A and B. The second problem: how to remove all zeros in a matrix. D=[1 2 3; 1 7 2; 6 2 7,0 0 0,0 0 0].
Wesley on 1 Jun 2021
The first problem has been solved.
coefficients = polyfit([x1, x2], [y1, y2], 1);
a = coefficients (1);
b = coefficients (2);

Sulaymon Eshkabilov on 1 Jun 2021
Question (1) is a simple LA exercise, but [A] needs to be 2-by-2. And then you can compute the roots of the system using linsolve(), ldivide(), \, etc operators.
Question (2): again the size of D is incorrectly defined. number of elements in each row has to be equal. Or D has to be row or column matrix containing some "0" elements. Once you fix this issue, you can solve the problem using logical indexing, e.g.: D(D==0) = [ ].
Wesley on 1 Jun 2021
Thank you very much for your kind answer. I upload files such as D.mat, using your method can not remove 0.I don't know where my mistake is.
Wesley on 1 Jun 2021
I don't know why two columns become one.