[matlab] Take a certain row and a certain column of the matrix

1. Operation instructions

Take a certain row: Ki = K( i , : );
Take a certain column: Kj = K( : , j );
Take a certain number of rows: Kij = K( i : j , : );
Take a certain number of columns:Kij = K( : , i : j );

iand jrepresent the number of rows and columns

2. Example analysis

For example, matrix K=[1 2 3; 4 5 6 ; 7 8 9], three rows and three columns.

K =[1 2 3 ;
    4 5 6 ;
    7 8 9];
    
%取K第一行
K1=K( 1 , : );
%取K第二列
K2=K( : , 2 );
%取第二三行
K23 = K( 2 : 3 , : );
%取K第一二列
K12 = K( : , 1 : 2 );

The returned result is:

>> K1

K1 =

     1     2     3

>> K2

K2 =

     2
     5
     8

>> K23

K23 =

     4     5     6
     7     8     9

>> K12

K12 =

     1     2
     4     5
     7     8