void palPolmo	(	double	elongm,
		double	phim,
		double	xp,
		double	yp,
		double *	elong,
		double *	phi,
		double *	daz
	)

Definition at line 135 of file palPolmo.c.

Referenced by t_polmo().

                                                          {

  double  sel,cel,sph,cph,xm,ym,zm,xnm,ynm,znm,
    sxp,cxp,syp,cyp,zw,xt,yt,zt,xnt,ynt;

  /*  Site mean longitude and mean geodetic latitude as a Cartesian vector */
  sel=sin(elongm);
  cel=cos(elongm);
  sph=sin(phim);
  cph=cos(phim);

  xm=cel*cph;
  ym=sel*cph;
  zm=sph;

  /*  Rotate site vector by polar motion, Y-component then X-component */
  sxp=sin(xp);
  cxp=cos(xp);
  syp=sin(yp);
  cyp=cos(yp);

  zw=(-ym*syp+zm*cyp);

  xt=xm*cxp-zw*sxp;
  yt=ym*cyp+zm*syp;
  zt=xm*sxp+zw*cxp;

  /*  Rotate also the geocentric direction of the terrestrial pole (0,0,1) */
  xnm=-sxp*cyp;
  ynm=syp;
  znm=cxp*cyp;

  cph=sqrt(xt*xt+yt*yt);
  if (cph == 0.0) xt=1.0;
  sel=yt/cph;
  cel=xt/cph;

  /*  Return true longitude and true geodetic latitude of site */
  if (xt != 0.0 || yt != 0.0) {
    *elong=atan2(yt,xt);
  } else {
    *elong=0.0;
  }
  *phi=atan2(zt,cph);

  /*  Return current azimuth of terrestrial pole seen from site position */
  xnt=(xnm*cel+ynm*sel)*zt-znm*cph;
  ynt=-xnm*sel+ynm*cel;
  if (xnt != 0.0 || ynt != 0.0) {
    *daz=atan2(-ynt,-xnt);
  } else {
    *daz=0.0;
  }

}

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