直接用简单的命令，我想不出来要怎么么写，只能用for循环来替代了
clc;clear;A = 1:9;A = reshape(A,3,3)'B = [ 1 1 ; 2 2 ; 3 3 ];a = size(B,1);for i = 1:a tmp(i) = A( B(i,1) , B(i,2) ); endmean(tmp)
