20120918 -- 可计算性

程序特性规定：

1 程序开始执行时，自认为一切变元的值为0

2 转向无定义符号，执行程序的最后一条指令 时 自动认为停机

 

y=x+3

y=x+1 y=x+1 y=x+1 y=x

 

 

n(x)=0

x=x+1

 

y=x1+x2

y=x1 [B] TO A IF x2 !=0 　　TO E [A] x2 = x2 -1 　　y=y+1 　　TO B

y=2x

TO C IF x!=0 TO E [C] TO A IF x!=0 [B] y=y+1 z=z-1 TO B IF z!=0 TO E [A]x=x-1 y=y+1 z=z+1 TO C

y=x1*x2

[B]TO A IF x2 != 0 TO E [A]x2=x2-1 y=y+x1 TO B

[A] TO B IF x1 != 0 TO E [B] TO C IF x2!=0 TO E [C] y=y+x1 z=z+1 x2=x2-1 TO B

y=[x1/x2]

算法思想：

输入x1,连续的减去x2,若x1-x2 还有余，则输出y=y+1.若刚好减完，则输出y。减完后x2以后，若x1仍能够减，重复操做，知道x1剩余小于x2，再也不同步减

z1=z1+1 .......执行x2次，进行赋值 TO A IF x1 != 0 TO E [A] z2= z1 y=y+1 [B]x1=x1-1 z2=z2-1 TO C IF z2 != 0 TO A IF x1 != 0 [C]TO B IF x1 != 0 y=y-1 TO E 

y=根号X

算法思想：

x-(2y+1)-(2y+1)......每次分步执行   x-y1-y1-1

TO A IF x!=0 TO E [A] z1= z1+1 z1=z1+1 [F] TO B IF z1 != 0 x=x-1 TO G IF x!=0 y=y+1 TO E [B] z2 = y TO C IF z2 != 0 z1 = z1 -1 TO F [C] x= x-1 z2 = z2 -1 TO D IF x != 0 TO E [G] y= y+1 TO A