1.Matrix
A matrix is a set of vectors
If the matrix has m rows and n columns ,we say the size of the matrix is m by n,written m*n.
If m = n ,we call this matrix "square".We use to donote the set that cotains all matrices whose size is m*n.eg:
has 3 rows and 2 columns.
2.The use of Matrix
2.1add and subtract
Two Matrixs with the same size(the number of rows and columns) can add and subtract(减).
2.2multiply
Matrix can multiply with a scalar.
2.3Zero Matrix(零矩阵) and Identity Matrix(单位矩阵)
(1)Zero Matrix:All elments are 0,which we donoted by O.
(2) Identity Matrix:It must be square ,对角线是1，其他全是0.
2.4Properties
Properties
3.Transpose
If A is an mxn matrix,(transpose of A) is an nxm matrix whose (i,j)-entry is the (j-i)-entry of A.(行列互换)
3.1Properties
Properties
