第三十八题

题目

求一个3*3矩阵主对角线元素之和。

import numpy as np
a = np.zeros((3,3))
for i in range(0,3):
    for j in range(0,3):
        a[i,j] = input('please input the number of index (%i,%i): '%(i,j))

item = [-2,-1,0,1,2];
for z in item:
    su = 0
    for i in range(0,3):
        for j in range(0,3):
            if i-j == z:
                su = su + a[i,j]
                print('(%i,%i)	'%(i,j),end='')
    print('Diagonal element addition: %0.2f'%su);