学步园

float get_variance(float*a,int n)
{
	float mean,sum1=0;
	int i;
	for(i=0;i<=n-1;i++) 
	{ 
		sum1+=a[i]; 
	} 
	mean=sum1/n;

	float variance,sum2=0;
	for (i=0;i<=n-1;i++) 
	{ 
		sum2+=(a[i]-mean)*(a[i]-mean); 
	} 
	variance=sum2/n;
	return variance;
}