code4sk/c/sourcecode/朱森森带领的奇妙冒险/2022-2023第二学期单开班第1次月考/7-3 求给定精度的简单交错序列部分和.cpp
2023-10-18 16:17:32 +08:00

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/*
7-3 ???????????????
?? 10
?? C???
?? ????
????????,??????? 1 - 1/4 + 1/7 - 1/10 + ... ?????????????????eps?
????:
?????????????eps?
????:
??????“sum = S”??????????S,???????????????????????????
????1:
4E-2
????1:
sum = 0.854457
????2:
0.02
????2:
sum = 0.826310
*/
#include<stdio.h>
int main(){
int flag=1;
double eps,a=1,sum=0;
scanf("%lf",&eps);
for(int i=1;;){
sum+=1.0/a*flag;
if(1.0/a<=eps)
break;
a+=3;
flag=-flag;
}
printf("sum = %.6lf",sum);
return 0;
}