Re: numerical analysis (composite numerical integration)

/* Slight improvement: */
double trapezoidal_rule(double a, double b, int n, double (*f)
(double))
{
double h = (b - a) / n;
double area = f(a);
double midpart = 0;
unsigned i;

for (i = 1; i < n; i++) {
midpart += f(a + i * h);
}
midpart *= 2.0;
return (area + midpart + f(b)) * h * 0.5;
}

.