Matrix multiplication

Matrix multiplication is the operation of creating a new matrix from two matrices according to certain rules. The key requirement is that the number of columns in the left matrix must equal the number of rows in the right matrix; otherwise, you can't calculate it. When calculating, the resulting matrix has the same number of rows as the left matrix and the same number of columns as the right matrix, and each element is obtained by multiplying and then adding the corresponding numbers from the row of the left matrix and the column of the right matrix.