Can a Singular Matrix Always Find a Partner Matrix to Result in Zero?

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In summary, if matrix A is singular, there will always exist a nonzero matrix B such that AB will be the zero matrix. This is because A has a null space and a column space, and any matrix with columns from the null space will satisfy the criterion for B. Additionally, the columns of A span the column space.
  • #1
ohyeahstar
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Just a small question, I think I may have missed this part out in our lectures or something. :|

Suppose I have a singular matrix A; will there always exist another matrix B such that AB (/BA) will be the zero matrix?
 
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  • #2
Yes, take B the zero matrix :smile: but you mean non-zero matrices, I suppose.

Well, if A is singular, then there always exists a nonzero column vector x such that Ax=0. Then B=(x x ... x) should do the trick.
 
  • #3
Welcome to PF ohyeahstar! :smile:

Yep, as mm said!

More specifically, a matrix has a so called "null space" (or "kernel space") and a so called "column space" (or "image" or "range" of the matrix).
Any matrix with columns selected from the null space will satisfy your criterion for B.
Furthermore the columns from your matrix A "span" the column space.
 

Related to Can a Singular Matrix Always Find a Partner Matrix to Result in Zero?

1. What is a singular matrix?

A singular matrix is a square matrix that does not have an inverse. This means that it cannot be multiplied by another matrix to produce the identity matrix (a matrix with 1s along the main diagonal and 0s everywhere else).

2. How can you tell if a matrix is singular?

A matrix is singular if its determinant (a numerical value that can be calculated from the elements of the matrix) is equal to 0. This can be determined by using various methods such as Gaussian elimination or finding the eigenvalues of the matrix.

3. What are the implications of having a singular matrix?

Having a singular matrix can cause problems in certain mathematical operations, as the matrix does not have an inverse. This can make solving systems of equations or finding the inverse of a larger matrix impossible.

4. Can a singular matrix have any non-zero elements?

Yes, a singular matrix can have non-zero elements. The singularity of a matrix is dependent on its determinant, not the values of its elements. However, a matrix with all non-zero elements is never singular.

5. How can singular matrices be used in real-world applications?

Singular matrices are commonly used in computer graphics and image processing, as they can represent transformations that are not invertible. They can also be used in optimization problems, where the singular value decomposition (a mathematical process that breaks down a matrix into simpler components) can be used to find the optimal solution.

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