梯形求积公式和辛普生求积公式的误差公别是？

int main()
{
int a=1 ;
int b=2 ;
int n=100 ;
double h = 0.01 ;

double xk = 0 ;
double xk1 = 0 ;
double xk12 = 0 ;
double i = 0 ;

for ( int k =0; k<=n-1; k++ )
{
xk = a + k*h ;
xk12 = xk + h/2 ;
xk1 = xk + h ;

i = i + f(xk) + 4*f(xk12) + f( xk1 ) ;
}

i = i * h/6 ;

cout << " the value is " << i << endl;

cout << " Done ! " << endl;
return 0 ;

什么是辛普生求积公式？