Geometry Related functions C++

///geometry related
template <typename T> inline T cylinder_3D_volume(T r, T h) { return PI*r*r*h; }
template <typename T> inline T sphere_3D_volume(T r) { return (4.0/3.0)*PI*r*r*r; }
template <typename T> inline T cone_3D_volume(T r, T h) { return (1.0/3.0)*PI*r*r*h; }
template <typename T> inline T ellipsoid_3D_volume(T r1,T r2,T r3) { return (4.0/3.0)*PI*r1*r2*r3; }
template <typename T> inline T pointDistance_2D(T x1,T y1,T x2, T y2) { return sqrt(SQR_D(x2-x1) + SQR_D(y2-y1)); }
template <typename T> inline T pointDistance_3D(T x1,T y1,T z1,T x2,T y2,T z2) { return sqrt(SQR_D(x2-x1) + SQR_D(y2-y1) + SQR_D(z2-z1)); }