void palRefv	(	double	vu[3],
		double	refa,
		double	refb,
		double	vr[3]
	)

Definition at line 129 of file palRefv.c.

References DMAX.

Referenced by t_ref().

                                                                      {

  double x,y,z1,z,zsq,rsq,r,wb,wt,d,cd,f;

  /*  Initial estimate = unrefracted vector */
  x = vu[0];
  y = vu[1];
  z1 = vu[2];

  /*  Keep correction approximately constant below about 3 deg elevation */
  z = DMAX(z1,0.05);

  /*  One Newton-Raphson iteration */
  zsq = z*z;
  rsq = x*x+y*y;
  r = sqrt(rsq);
  wb = refb*rsq/zsq;
  wt = (refa+wb)/(1.0+(refa+3.0*wb)*(zsq+rsq)/zsq);
  d = wt*r/z;
  cd = 1.0-d*d/2.0;
  f = cd*(1.0-wt);

  /*  Post-refraction x,y,z */
  vr[0] = x*f;
  vr[1] = y*f;
  vr[2] = cd*(z+d*r)+(z1-z);
}

Here is the caller graph for this function: