近似计算π值

通过James Gregory的展开式，π/4=1-1/3+1/5-1/7…公式, 计算π近似值

#include <stdio.h>

double pai(double accuracy)
{
    if(accuracy<=0 || accuracy>1) return 3;
    int symbol = 1; //项正负标志
    int n = 1; //分母项
    double pi = 0.0;
    do
    {
        pi += symbol * (1.0 / n);
        n += 2;
        symbol = -symbol;
    }while(1.0/n >= accuracy*0.1 );
    return pi*4;
}

int main()
{
    double accuracy , pi;
    scanf("%lf", &accuracy );
    printf("accuracy: %f\n", accuracy);
    pi = pai(accuracy);
    printf("%f\n", pi);
    return 0;
}

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