qgaus.h

来自「经典numerical receip 配套代码」· C头文件 代码 · 共 17 行

template <class T>
Doub qgaus(T &func, const Doub a, const Doub b)
{
	static const Doub x[]={0.1488743389816312,0.4333953941292472,
		0.6794095682990244,0.8650633666889845,0.9739065285171717};
	static const Doub w[]={0.2955242247147529,0.2692667193099963,
		0.2190863625159821,0.1494513491505806,0.0666713443086881};
	Doub xm=0.5*(b+a);
	Doub xr=0.5*(b-a);
	Doub s=0;
	for (Int j=0;j<5;j++) {
		Doub dx=xr*x[j];
		s += w[j]*(func(xm+dx)+func(xm-dx));
	}
	return s *= xr;
}