Solve matrix equations using loop

Question

Alina Abdikadyr 2022-10-8

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1820070-solve-matrix-equations-using-loop

评论： Torsten 2022-10-8

Hello everyone!

I have a matrix A(3x3)

A= (2 10 15

3 5 -7

3 -2 -2 )

And Matrx B (3x1)

B = (B1

B2

B3)

Matrix C (3x1), where all values are equal to each other

C= (C1

C1

C1)

So, I need using loop, solve the equations and find the values of C1, B2 and B3. B1 is known for me, and has 125 elements. For each B1, I have to find C1, B2 and B3 respectively

Solve the equation A*B=C

Thank you in advance!

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Alina Abdikadyr 2022-10-8

A*B=C

Torsten 2022-10-8

Didn't you like my solution ?

https://de.mathworks.com/matlabcentral/answers/1816340-extract-values-from-one-matrix-and-with-iteration-solve-the-system-of-linear-equations?s_tid=prof_contriblnk

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Answer 1

Chunru 2022-10-8

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https://ww2.mathworks.cn/matlabcentral/answers/1820070-solve-matrix-equations-using-loop#answer_1069400

在 MATLAB Online 中打开

The equations you have:

You want to solve it for

,

and

. You need to rearrage the equations:

Now you solve this new system of equations with unknowns as

:

A = [  2 10  15
      3   5  -7
      3  -2  -2 ];
Anew = [-ones(3, 1)  A(:, 2:3)];
AnewInv = inv(Anew);
b1 = rand(5,1);   % rand(125,1) or your data
for i=1:length(b1)
    bnew = -b1(i)*A(:, 1);
    res = AnewInv*bnew    %[c1; n2; b3]
end
res = 3×1
    0.9814
    0.0096
    0.0134
res = 3×1
    1.8311
    0.0178
    0.0250
res = 3×1
    0.9554
    0.0093
    0.0130
res = 3×1
    1.8897
    0.0184
    0.0258
res = 3×1
    0.4087
    0.0040
    0.0056