1、grid、box函数：设置网格线、边框
2、用法说明
（1）grid on/off 函数对当前坐标图加上或撤销网格线
（2）box on/off 函数对当前坐标图加上或撤销边框
（3）grid 函数在设置网格线和撤销网格线两种状态间进行转换
（4）box 函数在加上边框和撤销边框两种状态进行装换
3、用法举例
>> x = 1:200;
>> y = x.^2
y =
Columns 1 through 8
1 4 9 16 25 36 49 64
Columns 9 through 16
81 100 121 144 169 196 225 256
Columns 17 through 24
289 324 361 400 441 484 529 576
Columns 25 through 32
625 676 729 784 841 900 961 1024
Columns 33 through 40
1089 1156 1225 1296 1369 1444 1521 1600
Columns 41 through 48
1681 1764 1849 1936 2025 2116 2209 2304
Columns 49 through 56
2401 2500 2601 2704 2809 2916 3025 3136
Columns 57 through 64
3249 3364 3481 3600 3721 3844 3969 4096
Columns 65 through 72
4225 4356 4489 4624 4761 4900 5041 5184
Columns 73 through 80
5329 5476 5625 5776 5929 6084 6241 6400
Columns 81 through 88
6561 6724 6889 7056 7225 7396 7569 7744
Columns 89 through 96
7921 8100 8281 8464 8649 8836 9025 9216
Columns 97 through 104
9409 9604 9801 10000 10201 10404 10609 10816
Columns 105 through 112
11025 11236 11449 11664 11881 12100 12321 12544
Columns 113 through 120
12769 12996 13225 13456 13689 13924 14161 14400
Columns 121 through 128
14641 14884 15129 15376 15625 15876 16129 16384
Columns 129 through 136
16641 16900 17161 17424 17689 17956 18225 18496
Columns 137 through 144
18769 19044 19321 19600 19881 20164 20449 20736
Columns 145 through 152
21025 21316 21609 21904 22201 22500 22801 23104
Columns 153 through 160
23409 23716 24025 24336 24649 24964 25281 25600
Columns 161 through 168
25921 26244 26569 26896 27225 27556 27889 28224
Columns 169 through 176
28561 28900 29241 29584 29929 30276 30625 30976
Columns 177 through 184
31329 31684 32041 32400 32761 33124 33489 33856
Columns 185 through 192
34225 34596 34969 35344 35721 36100 36481 36864
Columns 193 through 200
37249 37636 38025 38416 38809 39204 39601 40000
>> plot(x,y)
（1）grid on
>> grid on
（2）grid off
>> grid off
（3）box on
>> box on
（4）box off
>> box off
