自适应辛普森法

自适应辛普森法

double a, b, c, d, l, r;const double eps = 1e-8;
double F(double x) {//需要积分的公式return (c * x + d) / (a * x + b);
}
double simpson(double l, double r) {double mid = (l + r) / 2;return (F(l) + 4 * F(mid) + F(r)) * (r - l) / 6;
}
double asr(double l, double r, double A) {double mid = (l + r) / 2;double L = simpson(l, mid), R = simpson(mid, r);if (fabs(L + R - A) <= 15 * eps)return L + R + (L + R - A) / 15.0;return asr(l, mid, L) + asr(mid, r, R);
}
double asr(double l, double r) {return asr(l, r, simpson(l, r));
}