Horizontal Equ2Hor ( double Dec, double tau, double lat)
{
//
// Variables
//
Vec3D e_equ;
Polar e_hor;
Horizontal result;
Polar polar=new Polar(tau,Dec);
e_equ = new Vec3D(polar); // unit vector in horizontal system
// e_equ = {m_Vec = {0.58881464761003832, -0.38575765187682981, 0.71027342958774764}, m_phi = -0.57998202437182178, m_theta = 0.78988656845716043, m_r = 1, m_bPolarValid = true}
// R_y(pi/2.0-lat)={m_Mat = {{0.74431154623115414, 0, -0.66783255547104659}, {0, 1, 0}, {0.66783255547104659, 0, 0.74431154623115414}}}
e_hor=APC_Vect3D.calcPolarAngles (APC_Vect3D.AbProduct(APC_Vect3D.R_y(Math.PI/2.0-lat), e_equ)); // unit vector in equatorial system
// e_hor = {m_Vec = {-0.036082178758590183, -0.38575765187682981, 0.92189430543555695}, m_phi = 0, m_theta = 0, m_r = 0, m_bPolarValid = false}