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What is the difference between square matrix and matrix? What is the multiplication rule of matrix? RT
Square matrix belongs to matrix, which is a special matrix with equal number of rows and columns
Matrix multiplication rule: the left matrix determines the number of rows, the right matrix determines the number of columns, and the number of columns in the left matrix equals the number of rows in the right matrix
Matrix multiplication
Let a = (AIJ) be the sum of M rows and s columns
B = (bij) is the sum of s rows and N columns
Then a and B can be multiplied and the result is a matrix with M rows and N columns
Let AB = C = (CIJ)
Then the elements in the i-th row and j-th column of AB = the sum of the elements in the i-th row of a and the elements in the j-th column of B respectively
That is CIJ = ai1b1j + ai2b2j +... + aisbsj
What is the meaning of matrix multiplication?
We can't say that matrix multiplication has any meaning
You first understand that matrix is used to record a large number of data tools, is a place to store data, concise, no matter how many dimensions you are!
When there is a certain relationship between the data of two or more matrices (such as the product of multiple vectors), we can consciously put them in the matrix to do multiplication, which can save a lot of cumbersome symbols
If there is any significance in matrix multiplication, that is, the law that makes the multiplication of multidimensional arrays with relations change, it is related to writing and recording
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