Question

有一分数序列;2/1,3/2,5/3,8/5,13/8,21/13·······求这个数列的前20项之和，用函数编写程序

Answer 1

#include<stdo.h>
void main()
{ int i;
double f1=2,f1=1,s=0,t;
for(i=1;i<=20;i++)
{ s=s+f1/f2;
t=f1,f1+f2,f2=t;

}printf("sum=%f\n",s);

}

Answer 2

F(n) = (1/2)*((sqrt(5)+1)^(n+2)-(1-sqrt(5))^(n+2))/((sqrt(5)+1)^(n+1)-(1-sqrt(5))^(n+1))