MATLAB: Inverse and identity matrix

columnidentitymatrixsaiz

Given. A=[1 2 3;6 7 8;11 12 13]; B=[4 5 6;9 10 11;14 15 16]; and C=-inv(A)*B/eye(3). And the C matrix is
C =
     4     8     8
     0     0    -8
     0     0     4
The size of C matrix must be 6×3.But I only got 3×3. Why does it happen?

Best Answer

It happens because of the basic rules of those matrix operators.
All of your matrices are 3x3. Both of those binary operations (* and /) between 3x3 matrices result in another 3x3 matrix.
My guess is you have invented in your mind a new rule for the / operator, wherein it becomes a matrix concatenation operator, or something like that. Sorry, but operators have explicit definitions in MATLAB. They follow their defined behaviors, as I would hope they should.
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