Asked by Michael
on 16 Oct 2014

Hello Everyone,

I am currently working on trying to solve a System of Linear Equations, but MATLAB keeps on returning all zeroes. This is because all of the elements in the second matrix (on the answer side of the linear equations) are zeroes, but that is the only thing I am allowed to work with.

Here is the code:

--------------------------------------------------------

sysEq = [1/sqrt(35), -3/sqrt(34), 1/sqrt(42); 3/sqrt(35), 0, -4/sqrt(42); 5/sqrt(35), 5/sqrt(34), 5/sqrt(42)]

sysEqAns = [0, 0, 0]';

Ans = sysEq\sysEqAns

---------------------------------------------------------

If anyone knows how to resolve this complication, I'd be very grateful.

Thanks, Mike

Answer by Mischa Kim
on 16 Oct 2014

Edited by Mischa Kim
on 16 Oct 2014

Accepted Answer

Michael, the answer (zero-vector) is correct. If you do

rank(sysEq)

you'll see that the matrix has full rank (= 3). This means that the rows (and columns) of the matrix are linearly independent which in turn means that only Ans = [0 0 0]' multiplied by the matrix will result in the zero-vector sysEqAns = [0 0 0]'. In other words, there is no other solution for Ans that results in the zero-vector for sysEqAns.

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## 2 Comments

## Guillaume (view profile)

Direct link to this comment:https://www.mathworks.com/matlabcentral/answers/158817-problem-using-left-hand-division-in-matlab#comment_243398

## Mischa Kim (view profile)

Direct link to this comment:https://www.mathworks.com/matlabcentral/answers/158817-problem-using-left-hand-division-in-matlab#comment_243401

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