[h,az]=equ2hor(dec,tau,phi)

function [h,az]=equ2hor(dec,tau,phi)

% function [h,az]=equ2hor(dec,tau,phi)
%
% transformation from equatorial coordinates to the horizon system
% algorithms by Montenbruck/Pfleger: "Astronomy with the Personal Computer"
%
% 05.05.04 M.Penzkofer

rho = pi/180;

CS_phi=cos(phi*rho); SN_phi=sin(phi*rho);
CS_dec=cos(dec*rho); SN_dec=sin(dec*rho);
CS_tau=cos(tau*rho); SN_tau=sin(tau*rho);
x = CS_dec*SN_phi*CS_tau - SN_dec*CS_phi;
y = CS_dec*SN_tau;
z = CS_dec*CS_phi*CS_tau + SN_dec*SN_phi;
[DUMMY,h,az]=cart2pol(x,y,z);