收敛速度惊人
#include <stdio.h>
/* 自然对数的底e = 2.718281828... */
double GenerateBaseE(const size_t N) {
double ret = 1.0;
unsigned long long k = 1;
for (size_t i = 1; i <= N; ++i) {
k *= i;
ret += 1.0 / k;
}
return ret;
}
int main(int argc, char* argv[]) {
printf("exp = %.9f\n", GenerateBaseE(14));
return 0;
}