C语言程序:
#include <stdio.h>
#include <math.h>
int main()
{
double x;
double sum1, sum2, f = 1;
int i, t = 1;
printf("x:");
scanf("%lf", &x);
i = 1;
sum1 = sum2 = 1;
for(i=2; ; i*=2)
{
f *= (i -1);
f *= i;
t *= -1;
sum2 += t * pow(x, i) / f;
if(abs(sum2 - sum1) < 1e-6)
{
break;
}
sum1 = sum2;
}
printf("cos(%lf) = %lf\n", x, sum2);
return 0;
}
运行测试:
x:2
cos(2.000000) = -0.333333