// general inverse projection
// inverse projection entry
public static LP pj_inv(XY xy, PJ P)
{
LP lp;
// can't do as much preliminary checking as with forward
if(xy.x==Libc.HUGE_VAL||xy.y==Libc.HUGE_VAL)
{
lp.lam=lp.phi=Libc.HUGE_VAL;
pj_ctx_set_errno(P.ctx, -15);
return lp;
}
Libc.errno=pj_errno=0;
P.ctx.last_errno=0;
xy.x=(xy.x*P.to_meter-P.x0)*P.ra; // descale and de-offset
xy.y=(xy.y*P.to_meter-P.y0)*P.ra;
lp=P.inv(xy); // inverse project
if(P.ctx.last_errno!=0)
{
lp.lam=lp.phi=Libc.HUGE_VAL;
}
else
{
lp.lam+=P.lam0; // reduce from del lp.lam
if(!P.over) lp.lam=adjlon(lp.lam); // adjust longitude to CM
if(P.geoc&&Math.Abs(Math.Abs(lp.phi)-HALFPI)>EPS12)
lp.phi=Math.Atan(P.one_es*Math.Tan(lp.phi));
}
return lp;
}