When Does Matrix Multiplication Not Work?

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In summary, matrix multiplication only works for matrices with the same number of columns in the first matrix as rows in the second matrix. It can be performed on non-square matrices, but the resulting matrix will have a different size. There are no special rules for multiplying matrices with complex numbers, except that the resulting matrix will also have complex numbers. Matrix multiplication is not commutative, but it is associative. There are no restrictions on the values in a matrix for matrix multiplication to work, as long as the number of columns in the first matrix matches the number of rows in the second matrix.
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j-lee00
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simple matrix question


For Matrix A; size (3 x 1)
Matrix B; size (1 x 3)

AB = (3 x 3)

But when does matrix multiplication not work?
 
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Matrix multiplication does not work when the number of columns in the first matrix is not equal to the number of rows in the second matrix.
 
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Cheers
 

1. Why does matrix multiplication not work for matrices with different sizes?

Matrix multiplication only works for matrices with the same number of columns in the first matrix as rows in the second matrix. If the matrices have different sizes, the number of columns and rows will not match up, making it impossible to multiply them.

2. Can matrix multiplication be performed on non-square matrices?

Yes, matrix multiplication can be performed on non-square matrices as long as the number of columns in the first matrix is equal to the number of rows in the second matrix. However, the resulting matrix will have a different size from the original matrices.

3. Are there any special rules for multiplying matrices with complex numbers?

No, the same rules for matrix multiplication apply to matrices with complex numbers. The only difference is that the resulting matrix will also have complex numbers.

4. Can matrix multiplication be done in any order?

No, matrix multiplication is not commutative, meaning that the order of the matrices matters. Multiplying A x B is not the same as multiplying B x A. However, it is associative, meaning that (A x B) x C is equal to A x (B x C).

5. Are there any restrictions on the values in a matrix for matrix multiplication to work?

No, matrix multiplication can be performed on matrices with any type of values, as long as the number of columns in the first matrix matches the number of rows in the second matrix. The resulting values may be different depending on the type of values in the matrices, but the multiplication will still work.

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