MATLAB循环

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1. 观察一下语句,计算每个循环的循环次数和循环结束之后 x 的值
(1)
x = 1;
while mod(x,10)~=0
x=x+1;
end
解:>> x = 1;
n=0;
while mod(x,10)~=0
x=x+1;
n=n+1;
end
disp(x);disp(n);
10
9
(2)
x = 0;
for i=1:100
x = x + i;
end
解:>> x = 0;
n=0;
for i=1:100
x = x + i;
n=n+1;
end
disp(x);disp(n);
5050
100
(3)
x = 200;
while x > 0
if mod(x,7) == 0
break;
end
x = x -1;
end
解:>> x = 200;
n=0;
while x > 0
if mod(x,7) == 0
break;
end
x = x -1;
n=n+1;
end
disp(x);disp(n);
196
4
(4)
x = 500;
while x > 0
if isprime(x)
break;
end
x = x -1;
end
解:>> x = 500;
n=0;
while x > 0
if isprime(x)
break;
end
x = x -1;
n=n+1;
end
disp(x);disp(n);
499
1

2. 编写程序计算335050xxfxxx的值,其中x的值为 -10 到 10 之间,以 0.5
为步长,通过循环语句实现
解:>> for x=-10:0.5:10
if x>=0
y=x.^3+5
else y=-x.^3+5
end
x
end

y =
1005
x =
-10
y =
862.3750
x =
-9.5000
y =
734
x =
-9
y =
619.1250
x =
-8.5000
y =
517
x =
-8
y =
426.8750
x =
-7.5000
y =
348
x =
-7
y =
279.6250
x =
-6.5000
y =
221
x =
-6
y =
171.3750
x =
-5.5000
y =
130
x =
-5
y =
96.1250
x =
-4.5000
y =
69
x =
-4
y =
47.8750
x =
-3.5000
y =
32
x =
-3
y =
20.6250
x =
-2.5000
y =
13
x =
-2
y =
8.3750
x =
-1.5000
y =
6
x =
-1
y =
5.1250
x =
-0.5000
y =
5
x =
0
y =
5.1250
x =
0.5000
y =
6
x =
1
y =
8.3750
x =
1.5000
y =
13
x =
2
y =
20.6250
x =
2.5000
y =
32
x =
3
y =
47.8750
x =
3.5000
y =
69
x =
4
y =
96.1250
x =
4.5000
y =
130
x =
5
y =
171.3750
x =
5.5000
y =
221
x =
6
y =
279.6250
x =
6.5000
y =
348
x =
7
y =
426.8750
x =
7.5000
y =
517
x =
8
y =
619.1250
x =
8.5000
y =
734
x =
9
y =
862.3750
x =
9.5000
y =
1005
x =
10

3. 利用 random 函数编写一个新的函数 randomn,该函数能够产生,nn之间的随机

数,其中 n 为任意正数。该函数以 random 函数为子函数。

4. 重新编写程序,实现 3 中的功能,不采用循环语句,使用变量方式实现,并且比较两
个程序的运行效率