public static LP pj_gauss(projCtx ctx, LP elp, GAUSS en)
{
LP slp;
slp.phi=2.0*Math.Atan(en.K*Math.Pow(Math.Tan(0.5*elp.phi+Proj.FORTPI), en.C)*srat(en.e*Math.Sin(elp.phi), en.ratexp))-Proj.HALFPI;
slp.lam=en.C*elp.lam;
return slp;
}
public static LP pj_inv_gauss(projCtx ctx, LP slp, GAUSS en)
{
const int MAX_ITER = 20;
LP elp;
elp.phi = 0;
elp.lam = slp.lam / en.C;
double num = Math.Pow(Math.Tan(0.5 * slp.phi + Proj.FORTPI) / en.K, 1.0 / en.C);
int i = MAX_ITER;
for (; i > 0; i--)
{
elp.phi = 2.0 * Math.Atan(num * srat(en.e * Math.Sin(slp.phi), -0.5 * en.e)) - Proj.HALFPI;
if (Math.Abs(elp.phi - slp.phi) < TOL14)
{
break;
}
slp.phi = elp.phi;
}
// convergence failed
if (i == 0)
{
Proj.pj_ctx_set_errno(ctx, -17);
}
return(elp);
}
public static LP pj_gauss(projCtx ctx, LP elp, GAUSS en)
{
LP slp;
slp.phi = 2.0 * Math.Atan(en.K * Math.Pow(Math.Tan(0.5 * elp.phi + Proj.FORTPI), en.C) * srat(en.e * Math.Sin(elp.phi), en.ratexp)) - Proj.HALFPI;
slp.lam = en.C * elp.lam;
return(slp);
}
public override PJ Init()
{
double R;
en=GAUSS.pj_gauss_ini(e, phi0, out phic0, out R);
if(en==null) return null;
sinc0=Math.Sin(phic0);
cosc0=Math.Cos(phic0);
R2=2.0*R;
inv=e_inverse;
fwd=e_forward;
return this;
}
public static LP pj_inv_gauss(projCtx ctx, LP slp, GAUSS en)
{
const int MAX_ITER=20;
LP elp;
elp.phi=0;
elp.lam=slp.lam/en.C;
double num=Math.Pow(Math.Tan(0.5*slp.phi+Proj.FORTPI)/en.K, 1.0/en.C);
int i=MAX_ITER;
for(; i>0; i--)
{
elp.phi=2.0*Math.Atan(num*srat(en.e*Math.Sin(slp.phi), -0.5*en.e))-Proj.HALFPI;
if(Math.Abs(elp.phi-slp.phi)<TOL14) break;
slp.phi=elp.phi;
}
// convergence failed
if(i==0) Proj.pj_ctx_set_errno(ctx, -17);
return elp;
}
public static GAUSS pj_gauss_ini(double e, double phi0, out double chi, out double rc)
{
chi = rc = 0;
try
{
GAUSS en = new GAUSS();
double es = e * e;
en.e = e;
double sphi = Math.Sin(phi0);
double cphi = Math.Cos(phi0);
cphi *= cphi;
rc = Math.Sqrt(1.0 - es) / (1.0 - es * sphi * sphi);
en.C = Math.Sqrt(1.0 + es * cphi * cphi / (1.0 - es));
chi = Math.Asin(sphi / en.C);
en.ratexp = 0.5 * en.C * e;
en.K = Math.Tan(0.5 * chi + Proj.FORTPI) / (Math.Pow(Math.Tan(0.5 * phi0 + Proj.FORTPI), en.C) * srat(en.e * sphi, en.ratexp));
return(en);
}
catch
{
return(null);
}
}
public static GAUSS pj_gauss_ini(double e, double phi0, out double chi, out double rc)
{
chi=rc=0;
try
{
GAUSS en=new GAUSS();
double es=e*e;
en.e=e;
double sphi=Math.Sin(phi0);
double cphi=Math.Cos(phi0);
cphi*=cphi;
rc=Math.Sqrt(1.0-es)/(1.0-es*sphi*sphi);
en.C=Math.Sqrt(1.0+es*cphi*cphi/(1.0-es));
chi=Math.Asin(sphi/en.C);
en.ratexp=0.5*en.C*e;
en.K=Math.Tan(0.5*chi+Proj.FORTPI)/(Math.Pow(Math.Tan(0.5*phi0+Proj.FORTPI), en.C)*srat(en.e*sphi, en.ratexp));
return en;
}
catch
{
return null;
}
}
