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# -*- coding: utf-8 -*- 

 

u'''A pure Python version of I{Karney}'s C++ classes U{Rhumb 

<https://GeographicLib.SourceForge.io/C++/doc/classGeographicLib_1_1Rhumb.html>} and U{RhumbLine 

<https://GeographicLib.SourceForge.io/C++/doc/classGeographicLib_1_1RhumbLine.html>}. 

 

Class L{RhumbLine} has been enhanced with methods C{intersection2} and C{nearestOn4} to find 

the intersection of two rhumb lines, respectively the nearest point on a rumb line. 

 

For more details, see the C++ U{GeographicLib<https://GeographicLib.SourceForge.io/C++/doc/index.html>} 

documentation, especially the U{Class List<https://GeographicLib.SourceForge.io/C++/doc/annotated.html>}, 

the background information on U{Rhumb lines<https://GeographicLib.SourceForge.io/C++/doc/rhumb.html>}, 

the utily U{RhumbSolve<https://GeographicLib.SourceForge.io/C++/doc/RhumbSolve.1.html>} and U{Online 

rhumb line calculations<https://GeographicLib.SourceForge.io/cgi-bin/RhumbSolve>}. 

 

Copyright (C) U{Charles Karney<mailto:Charles@Karney.com>} (2014-2022) 

and licensed under the MIT/X11 License. For more information, see the 

U{GeographicLib<https://GeographicLib.SourceForge.io>} documentation. 

''' 

# make sure int/int division yields float quotient 

from __future__ import division as _; del _ # PYCHOK semicolon 

 

from pygeodesy.basics import copysign0, neg, _xinstanceof, _zip 

from pygeodesy.constants import INT0, _EPSqrt as _TOL, NAN, PI_2, isnan, _0_0s, \ 

_0_0, _0_5, _1_0, _2_0, _4_0, _90_0, _180_0, _720_0 

# from pygeodesy.datums import _spherical_datum # in Rhumb.ellipsoid.setter 

from pygeodesy.errors import IntersectionError, itemsorted, _ValueError, \ 

_xdatum, _xkwds 

# from pygeodesy.etm import ExactTransverseMercator # in ._RhumbLine.xTM 

from pygeodesy.fmath import euclid, favg, fsum1_, hypot, hypot1 

# from pygeodesy.fsums import fsum1_ # from .fmath 

from pygeodesy.interns import NN, _azi12_, _coincident_, _COMMASPACE_, \ 

_intersection_, _lat1_, _lat2_, _lon1_, _lon2_, \ 

_no_, _s12_, _S12_, _under_name 

from pygeodesy.karney import _a12_, _atan2d, Caps, _CapsBase as _RhumbBase, \ 

_diff182, Direct9Tuple, _EWGS84, _fix90, GDict, \ 

_GTuple, Inverse10Tuple, _norm180 

from pygeodesy.ktm import KTransverseMercator, _Xorder, _Xs, \ 

_AlpCoeffs, _BetCoeffs # PYCHOK used! 

from pygeodesy.lazily import _ALL_DOCS, _ALL_LAZY, _ALL_MODS as _MODS 

from pygeodesy.namedTuples import Distance2Tuple, LatLon2Tuple, NearestOn4Tuple 

from pygeodesy.props import deprecated_method, Property, Property_RO, property_RO, \ 

_update_all 

from pygeodesy.streprs import Fmt, pairs, unstr 

from pygeodesy.units import Bearing as _Azi, Degrees as _Deg, Int, Lat, Lon, \ 

Meter as _M, Meter2 as _M2 

from pygeodesy.utily import sincos2_, sincos2d 

from pygeodesy.vector3d import _intersect3d3, Vector3d # in .intersection2 below 

 

from math import asinh, atan, cos, cosh, fabs, radians, sin, sinh, sqrt, tan 

 

__all__ = _ALL_LAZY.rhumbx 

__version__ = '22.09.15' 

 

_rls = [] # instances of C{RbumbLine} to be updated 

_TRIPS = 65 # .intersection2, 18+ 

 

 

class _Lat(Lat): 

'''(INTERNAL) Latitude B{C{lat}}. 

''' 

def __init__(self, *lat, **Error_name): 

kwds = _xkwds(Error_name, clip=0, Error=RhumbError) 

Lat.__new__(_Lat, *lat, **kwds) 

 

 

class _Lon(Lon): 

'''(INTERNAL) Longitude B{C{lon}}. 

''' 

def __init__(self, *lon, **Error_name): 

kwds = _xkwds(Error_name, clip=0, Error=RhumbError) 

Lon.__new__(_Lon, *lon, **kwds) 

 

 

def _update_all_rls(r): 

'''(INTERNAL) Zap cached/memoized C{Property[_RO]}s 

of any L{RhumbLine} instances tied to the given 

L{Rhumb} instance B{C{r}}. 

''' 

_xinstanceof(r, Rhumb) 

_update_all(r) 

for rl in _rls: # PYCHOK use weakref? 

if rl._rhumb is r: 

_update_all(rl) 

 

 

class Rhumb(_RhumbBase): 

'''Class to solve of the I{direct} and I{inverse rhumb} problems, accurately. 

 

@see: The U{Detailed Description<https://GeographicLib.SourceForge.io/C++/doc/ 

classGeographicLib_1_1Rhumb.html>} of I{Karney}'s C++ C{Rhumb Class}. 

''' 

_E = _EWGS84 

_exact = True 

_mRA = 6 

_mTM = 6 

 

def __init__(self, a_earth=_EWGS84, f=None, exact=True, name=NN, **RA_TMorder): 

'''New L{Rhumb}. 

 

@kwarg a_earth: This rhumb's earth (L{Ellipsoid}, L{Ellipsoid2}, 

L{a_f2Tuple}, L{Datum}, 2-tuple C{(a, f)}) or the 

(equatorial) radius (C{scalar}). 

@kwarg f: The ellipsoid's flattening (C{scalar}), iff B{C{a_earth}} is 

a C{scalar}, ignored otherwise. 

@kwarg exact: If C{True}, use an addition theorem for elliptic integrals 

to compute I{Divided differences}, otherwise use the Krüger 

series expansion (C{bool}), see also property C{exact}. 

@kwarg name: Optional name (C{str}). 

@kwarg RA_TMorder: Optional keyword arguments B{C{RAorder}} and B{C{TMorder}} 

to set the respective C{order}, see properties C{RAorder} 

and C{TMorder} and method C{orders}. 

 

@raise RhumbError: Invalid B{C{a_earth}}, B{C{f}} or B{C{RA_TMorder}}. 

''' 

if f is not None: 

self.ellipsoid = a_earth, f 

elif a_earth not in (_EWGS84, None): 

self.ellipsoid = a_earth 

if not exact: 

self._exact = False 

if name: 

self.name = name 

if RA_TMorder: 

self.orders(**RA_TMorder) 

 

@Property_RO 

def _A2(self): # Conformal2RectifyingCoeffs 

m = self.TMorder 

return _Xs(_AlpCoeffs, m, self.ellipsoid), m 

 

@Property_RO 

def _B2(self): # Rectifying2ConformalCoeffs 

m = self.TMorder 

return _Xs(_BetCoeffs, m, self.ellipsoid), m 

 

def _DConformal2Rectifying(self, x, y): # radians 

return _1_0 + (_sincosSeries(True, x, y, *self._A2) if self.f else _0_0) 

 

def Direct(self, lat1, lon1, azi12, s12, outmask=Caps.LATITUDE_LONGITUDE): 

'''Solve the I{direct rhumb} problem, optionally with the area. 

 

@arg lat1: Latitude of the first point (C{degrees90}). 

@arg lon1: Longitude of the first point (C{degrees180}). 

@arg azi12: Azimuth of the rhumb line (compass C{degrees}). 

@arg s12: Distance along the rhumb line from the given to 

the destination point (C{meter}), can be negative. 

 

@return: L{GDict} with 2 up to 8 items C{lat2, lon2, a12, S12, 

lat1, lon1, azi12, s12} with the destination point's 

latitude C{lat2} and longitude C{lon2} in C{degrees}, 

the rhumb angle C{a12} in C{degrees} and area C{S12} 

under the rhumb line in C{meter} I{squared}. 

 

@note: If B{C{s12}} is large enough that the rhumb line crosses 

a pole, the longitude of the second point is indeterminate 

and C{NAN} is returned for C{lon2} and area C{S12}. 

 

If the given point is a pole, the cosine of its latitude is 

taken to be C{epsilon}**-2 (where C{epsilon} is 2.0**-52. 

This position is extremely close to the actual pole and 

allows the calculation to be carried out in finite terms. 

''' 

rl = _RhumbLine(self, lat1, lon1, azi12, caps=Caps.LINE_OFF, 

name=self.name) 

return rl.Position(s12, outmask | self._debug) # lat2, lon2, S12 

 

@deprecated_method 

def Direct7(self, lat1, lon1, azi12, s12, outmask=Caps.LATITUDE_LONGITUDE_AREA): 

'''DEPRECATED, use method L{Rhumb.Direct8}. 

 

@return: A I{DEPRECATED} L{Rhumb7Tuple}. 

''' 

return self.Direct8(lat1, lon1, azi12, s12, outmask=outmask)._to7Tuple() 

 

def Direct8(self, lat1, lon1, azi12, s12, outmask=Caps.LATITUDE_LONGITUDE_AREA): 

'''Like method L{Rhumb.Direct} but returning a L{Rhumb8Tuple} with area C{S12}. 

''' 

return self.Direct(lat1, lon1, azi12, s12, outmask=outmask).toRhumb8Tuple() 

 

def DirectLine(self, lat1, lon1, azi12, name=NN, **caps): # caps=Caps.STANDARD 

'''Define a L{RhumbLine} in terms of the I{direct} rhumb problem. 

 

@arg lat1: Latitude of the first point (C{degrees90}). 

@arg lon1: Longitude of the first point (C{degrees180}). 

@arg azi12: Azimuth of the rhumb line (compass C{degrees}). 

@kwarg caps: Optional C{caps}, see L{RhumbLine} C{B{caps}}. 

 

@return: A L{RhumbLine} instance and invoke its method 

L{RhumbLine.Position} to compute each point. 

 

@note: Updates to this rhumb are reflected in the returned 

rhumb line. 

''' 

return RhumbLine(self, lat1=lat1, lon1=lon1, azi12=azi12, 

name=name or self.name, **caps) 

 

def _DIsometrict(self, phix, phiy, tphix, tphiy, _Dtan_phix_phiy): 

E = self.ellipsoid 

return _Dtan_phix_phiy * _Dasinh(tphix, tphiy) - \ 

_Dsin(phix, phiy) * _DeatanhE(sin(phix), sin(phiy), E) 

 

def _DIsometric2Rectifyingd(self, psix, psiy): # degrees 

if self.exact: 

E = self.ellipsoid 

phix, phiy, tphix, tphiy = _Eaux4(E.auxIsometric, psix, psiy) 

t = _Dtant(phix - phiy, tphix, tphiy) 

r = self._DRectifyingt( tphix, tphiy, t) / \ 

self._DIsometrict(phix, phiy, tphix, tphiy, t) 

else: 

x, y = radians(psix), radians(psiy) 

r = self._DConformal2Rectifying(_gd(x), _gd(y)) * _Dgd(x, y) 

return r 

 

def _DRectifyingt(self, tphix, tphiy, _Dtan_phix_phiy): 

E = self.ellipsoid 

tbetx = E.f1 * tphix 

tbety = E.f1 * tphiy 

return (E.f1 * _Dtan_phix_phiy * E.b * PI_2 

* _DfEt( tbetx, tbety, self._eF) 

* _Datan(tbetx, tbety)) / E.L 

 

def _DRectifying2Conformal(self, x, y): # radians 

return _1_0 - (_sincosSeries(True, x, y, *self._B2) if self.f else _0_0) 

 

def _DRectifying2Isometricd(self, mux, muy): # degrees 

E = self.ellipsoid 

phix, phiy, tphix, tphiy = _Eaux4(E.auxRectifying, mux, muy) 

if self.exact: 

t = _Dtant(phix - phiy, tphix, tphiy) 

r = self._DIsometrict(phix, phiy, tphix, tphiy, t) / \ 

self._DRectifyingt( tphix, tphiy, t) 

else: 

r = self._DRectifying2Conformal(radians(mux), radians(muy)) * \ 

_Dgdinv(E.es_taupf(tphix), E.es_taupf(tphiy)) 

return r 

 

@Property_RO 

def _eF(self): 

'''(INTERNAL) Get the ellipsoid's elliptic function. 

''' 

# .k2 = 0.006739496742276434 

return self._E._elliptic_e12 # _MODS.elliptic.Elliptic(-self._E._e12) 

 

@Property 

def ellipsoid(self): 

'''Get this rhumb's ellipsoid (L{Ellipsoid}). 

''' 

return self._E 

 

@ellipsoid.setter # PYCHOK setter! 

def ellipsoid(self, a_earth_f): 

'''Set this rhumb's ellipsoid (L{Ellipsoid}, L{Ellipsoid2}, L{Datum}, 

L{a_f2Tuple}, 2-tuple C{(a, f)}) or the (equatorial) radius (C{scalar}). 

''' 

E = _MODS.datums._spherical_datum(a_earth_f, Error=RhumbError).ellipsoid 

if self._E != E: 

_update_all_rls(self) 

self._E = E 

 

@property_RO 

def equatoradius(self): 

'''Get the C{ellipsoid}'s equatorial radius, semi-axis (C{meter}). 

''' 

return self.ellipsoid.a 

 

a = equatoradius 

 

@Property 

def exact(self): 

'''Get the I{exact} option (C{bool}). 

''' 

return self._exact 

 

@exact.setter # PYCHOK setter! 

def exact(self, exact): 

'''Set the I{exact} option (C{bool}). If C{True}, use I{exact} rhumb 

calculations, if C{False} results are less precise for more oblate 

or more prolate ellipsoids with M{abs(flattening) > 0.01} (C{bool}). 

 

@see: Option U{B{-s}<https://GeographicLib.SourceForge.io/C++/doc/RhumbSolve.1.html>} 

and U{ACCURACY<https://GeographicLib.SourceForge.io/C++/doc/RhumbSolve.1.html#ACCURACY>}. 

''' 

x = bool(exact) 

if self._exact != x: 

_update_all_rls(self) 

self._exact = x 

 

def flattening(self): 

'''Get the C{ellipsoid}'s flattening (C{float}). 

''' 

return self.ellipsoid.f 

 

f = flattening 

 

def Inverse(self, lat1, lon1, lat2, lon2, outmask=Caps.AZIMUTH_DISTANCE): 

'''Solve the I{inverse rhumb} problem. 

 

@arg lat1: Latitude of the first point (C{degrees90}). 

@arg lon1: Longitude of the first point (C{degrees180}). 

@arg lat2: Latitude of the second point (C{degrees90}). 

@arg lon2: Longitude of the second point (C{degrees180}). 

 

@return: L{GDict} with 5 to 8 items C{azi12, s12, a12, S12, 

lat1, lon1, lat2, lon2}, the rhumb line's azimuth C{azi12} 

in compass C{degrees} between C{-180} and C{+180}, the 

distance C{s12} and rhumb angle C{a12} between both points 

in C{meter} respectively C{degrees} and the area C{S12} 

under the rhumb line in C{meter} I{squared}. 

 

@note: The shortest rhumb line is found. If the end points are 

on opposite meridians, there are two shortest rhumb lines 

and the East-going one is chosen. 

 

If either point is a pole, the cosine of its latitude is 

taken to be C{epsilon}**-2 (where C{epsilon} is 2.0**-52). 

This position is extremely close to the actual pole and 

allows the calculation to be carried out in finite terms. 

''' 

r = GDict(name=self.name) 

if (outmask & Caps.AZIMUTH_DISTANCE_AREA): 

r.set_(lat1=lat1, lon1=lon1, lat2=lat2, lon2=lon2) 

E = self.ellipsoid 

psi1 = E.auxIsometric(lat1) 

psi2 = E.auxIsometric(lat2) 

psi12 = psi2 - psi1 

lon12, _ = _diff182(lon1, lon2) 

if (outmask & Caps.AZIMUTH): 

r.set_(azi12=_atan2d(lon12, psi12)) 

if (outmask & Caps.DISTANCE): 

a12 = hypot(lon12, psi12) * self._DIsometric2Rectifyingd(psi2, psi1) 

s12 = a12 * E._L_90 

r.set_(s12=s12, a12=copysign0(a12, s12)) 

if (outmask & Caps.AREA): 

r.set_(S12=self._S12d(lon12, psi2, psi1)) 

if ((outmask | self._debug) & Caps._DEBUG_INVERSE): # PYCHOK no cover 

r.set_(a=E.a, f=E.f, f1=E.f1, L=E.L, 

b=E.b, e=E.e, e2=E.e2, k2=self._eF.k2, 

lon12=lon12, psi1=psi1, exact=self.exact, 

psi12=psi12, psi2=psi2) 

return r 

 

# def Inverse3(self, lat1, lon1, lat2, lon2): # PYCHOK outmask 

# '''Return the distance in C{meter} and the forward and 

# reverse azimuths (initial and final bearing) in C{degrees}. 

# 

# @return: L{Distance3Tuple}C{(distance, initial, final)}. 

# ''' 

# r = self.Inverse(lat1, lon1, lat2, lon2) 

# return Distance3Tuple(r.s12, r.azi12, r.azi12) 

 

@deprecated_method 

def Inverse7(self, lat1, lon1, azi12, s12, outmask=Caps.AZIMUTH_DISTANCE_AREA): 

'''DEPRECATED, use method L{Rhumb.Inverse8}. 

 

@return: A I{DEPRECATED} L{Rhumb7Tuple}. 

''' 

return self.Inverse8(lat1, lon1, azi12, s12, outmask=outmask)._to7Tuple() 

 

def Inverse8(self, lat1, lon1, azi12, s12, outmask=Caps.AZIMUTH_DISTANCE_AREA): 

'''Like method L{Rhumb.Inverse} but returning a L{Rhumb8Tuple} with area C{S12}. 

''' 

return self.Inverse(lat1, lon1, azi12, s12, outmask=outmask).toRhumb8Tuple() 

 

def InverseLine(self, lat1, lon1, lat2, lon2, name=NN, **caps): # caps=Caps.STANDARD 

'''Define a L{RhumbLine} in terms of the I{inverse} rhumb problem. 

 

@arg lat1: Latitude of the first point (C{degrees90}). 

@arg lon1: Longitude of the first point (C{degrees180}). 

@arg lat2: Latitude of the second point (C{degrees90}). 

@arg lon2: Longitude of the second point (C{degrees180}). 

@kwarg caps: Optional C{caps}, see L{RhumbLine} C{B{caps}}. 

 

@return: A L{RhumbLine} instance and invoke its method 

L{RhumbLine.Position} to compute each point. 

 

@note: Updates to this rhumb are reflected in the returned 

rhumb line. 

''' 

r = self.Inverse(lat1, lon1, lat2, lon2, outmask=Caps.AZIMUTH) 

return RhumbLine(self, lat1=lat1, lon1=lon1, azi12=r.azi12, 

name=name or self.name, **caps) 

 

Line = DirectLine # synonyms 

 

def _MeanSinXi(self, x, y): # radians 

s = _Dlog(cosh(x), cosh(y)) * _Dcosh(x, y) 

if self.f: 

s += _sincosSeries(False, _gd(x), _gd(y), *self._RA2) * _Dgd(x, y) 

return s 

 

def orders(self, RAorder=None, TMorder=None): 

'''Get and set the I{RAorder} and/or I{TMorder}. 

 

@kwarg RAorder: I{Rhumb Area} order (C{int}, 4, 5, 6, 7 

or 8). 

@kwarg TMorder: I{Transverse Mercator} order (C{int}, 4, 

5, 6, 7 or 8). 

 

@return: L{RhumbOrder2Tuple}C{(RAorder, TMorder)} with 

the previous C{RAorder} and C{TMorder} setting. 

''' 

t = RhumbOrder2Tuple(self.RAorder, self.TMorder) 

if RAorder not in (None, t.RAorder): # PYCHOK attr 

self.RAorder = RAorder 

if TMorder not in (None, t.TMorder): # PYCHOK attr 

self.TMorder = TMorder 

return t 

 

@Property_RO 

def _RA2(self): 

# for WGS84: (0, -0.0005583633519275459, -3.743803759172812e-07, -4.633682270824446e-10, 

# RAorder 6: -7.709197397676237e-13, -1.5323287106694307e-15, -3.462875359099873e-18) 

m = self.RAorder 

return _Xs(_RACoeffs, m, self.ellipsoid, RA=True), m 

 

@Property 

def RAorder(self): 

'''Get the I{Rhumb Area} order (C{int}, 4, 5, 6, 7 or 8). 

''' 

return self._mRA 

 

@RAorder.setter # PYCHOK setter! 

def RAorder(self, order): 

'''Set the I{Rhumb Area} order (C{int}, 4, 5, 6, 7 or 8). 

''' 

n = _Xorder(_RACoeffs, RhumbError, RAorder=order) 

if self._mRA != n: 

_update_all_rls(self) 

self._mRA = n 

 

def _S12d(self, lon12, psi2, psi1): # degrees 

'''(INTERNAL) Compute the area C{S12}. 

''' 

r = (self.ellipsoid.areax if self.exact else 

self.ellipsoid.area) * lon12 / _720_0 

r *= self._MeanSinXi(radians(psi2), radians(psi1)) 

return r 

 

@Property 

def TMorder(self): 

'''Get the I{Transverse Mercator} order (C{int}, 4, 5, 6, 7 or 8). 

''' 

return self._mTM 

 

@TMorder.setter # PYCHOK setter! 

def TMorder(self, order): 

'''Set the I{Transverse Mercator} order (C{int}, 4, 5, 6, 7 or 8). 

 

@note: Setting C{TMorder} turns property C{exact} off. 

''' 

n = _Xorder(_AlpCoeffs, RhumbError, TMorder=order) 

if self._mTM != n: 

_update_all_rls(self) 

self._mTM = n 

self.exact = False 

 

def toStr(self, prec=6, sep=_COMMASPACE_, **unused): # PYCHOK signature 

'''Return this C{Rhumb} as string. 

 

@kwarg prec: The C{float} precision, number of decimal digits (0..9). 

Trailing zero decimals are stripped for B{C{prec}} values 

of 1 and above, but kept for negative B{C{prec}} values. 

@kwarg sep: Separator to join (C{str}). 

 

@return: Tuple items (C{str}). 

''' 

d = dict(ellipsoid=self.ellipsoid, RAorder=self.RAorder, 

exact=self.exact, TMorder=self.TMorder) 

return sep.join(pairs(itemsorted(d, asorted=False), prec=prec)) 

 

 

class RhumbError(_ValueError): 

'''Raised for an L{Rhumb} or L{RhumbLine} issue. 

''' 

pass 

 

 

class _RhumbLine(_RhumbBase): 

'''(INTERNAL) Class L{RhumbLine} 

''' 

_azi12 = _0_0 

# _lat1 = _0_0 

# _lon1 = _0_0 

_salp = _0_0 

_calp = _1_0 

_rhumb = None # L{Rhumb} instance 

 

def __init__(self, rhumb, lat1, lon1, azi12, caps=0, name=NN): # case=Caps.? 

'''New C{RhumbLine}. 

''' 

_xinstanceof(Rhumb, rhumb=rhumb) 

self._lat1 = _Lat(lat1=_fix90(lat1)) 

self._lon1 = _Lon(lon1= lon1) 

self._debug |= (caps | rhumb._debug) & Caps._DEBUG_DIRECT_LINE 

if azi12: # non-zero 

self.azi12 = azi12 

self._caps = caps 

if not (caps & Caps.LINE_OFF): 

_rls.append(self) 

n = name or rhumb.name 

if n: 

self.name=n 

self._rhumb = rhumb # last 

 

def __del__(self): # XXX use weakref? 

if _rls: # may be empty or None 

try: # PYCHOK no cover 

_rls.remove(self) 

except (TypeError, ValueError): 

pass 

self._rhumb = None 

# _update_all(self) # throws TypeError during Python 2 cleanup 

 

@Property 

def azi12(self): 

'''Get this rhumb line's I{azimuth} (compass C{degrees}). 

''' 

return self._azi12 

 

@azi12.setter # PYCHOK setter! 

def azi12(self, azi12): 

'''Set this rhumb line's I{azimuth} (compass C{degrees}). 

''' 

z = _norm180(azi12) 

if self._azi12 != z: 

if self._rhumb: 

_update_all(self) 

self._azi12 = z 

self._salp, self._calp = sincos2d(z) # no NEG0 

 

def distance2(self, lat, lon): 

'''Return the distance and (initial) bearing of a point 

to this rhumb line's start point. 

 

@arg lat: Latitude of the point (C{degrees}). 

@arg lon: Longitude of the points (C{degrees}). 

 

@return: A L{Distance2Tuple}C{(distance, initial)} with the C{distance} 

in C{meter} and C{initial} bearing in C{degrees}. 

 

@see: Methods L{RhumbLine.intersection2} and L{RhumbLine.nearestOn4}. 

''' 

r = self.rhumb.Inverse(self.lat1, self.lon1, lat, lon) 

# outmask=Caps.AZIMUTH_DISTANCE) 

return Distance2Tuple(r.s12, r.azi12) 

 

@Property_RO 

def ellipsoid(self): 

'''Get this rhumb line's ellipsoid (L{Ellipsoid}). 

''' 

return self.rhumb.ellipsoid 

 

@property_RO 

def exact(self): 

'''Get this rhumb line's I{exact} option (C{bool}). 

''' 

return self.rhumb.exact 

 

def intersection2(self, other, tol=_TOL, **eps): 

'''Iteratively find the intersection of this and an other rhumb line. 

 

@arg other: The other rhumb line ({RhumbLine}). 

@kwarg tol: Tolerance for longitudinal convergence (C{degrees}). 

@kwarg eps: Tolerance for L{intersection3d3} (C{EPS}). 

 

@return: A L{LatLon2Tuple}{(lat, lon)} with the C{lat}- and 

C{lon}gitude of the intersection point. 

 

@raise IntersectionError: No convergence for this B{C{tol}} or 

no intersection for an other reason. 

 

@see: Methods L{RhumbLine.distance2} and L{RhumbLine.nearestOn4} 

and function L{pygeodesy.intersection3d3}. 

 

@note: Each iteration involves a round trip to this rhumb line's 

L{ExactTransverseMercator} or L{KTransverseMercator} 

projection and invoking function L{intersection3d3} in 

that domain. 

''' 

_xinstanceof(other, _RhumbLine) 

_xdatum(self.rhumb, other.rhumb, Error=RhumbError) 

try: 

if other is self: 

raise ValueError(_coincident_) 

# make globals and invariants locals 

_diff = euclid # approximate length 

_i3d3 = _intersect3d3 # NOT .vector3d.intersection3d3 

_LL2T = LatLon2Tuple 

_xTMr = self.xTM.reverse # ellipsoidal or spherical 

_s_3d, s_az = self._xTM3d, self.azi12 

_o_3d, o_az = other._xTM3d, other.azi12 

# use halfway point as initial estimate 

p = _LL2T(favg(self.lat1, other.lat1), 

favg(self.lon1, other.lon1)) 

for i in range(1, _TRIPS): 

v = _i3d3(_s_3d(p), s_az, # point + bearing 

_o_3d(p), o_az, useZ=False, **eps)[0] 

t = _xTMr(v.x, v.y, lon0=p.lon) # PYCHOK Reverse4Tuple 

d = _diff(t.lon - p.lon, t.lat) # PYCHOK t.lat + p.lat - p.lat 

p = _LL2T(t.lat + p.lat, t.lon) # PYCHOK t.lon + p.lon = lon0 

if d < tol: 

return _LL2T(p.lat, p.lon, iteration=i, # PYCHOK p... 

name=self.intersection2.__name__) 

except Exception as x: 

raise IntersectionError(_no_(_intersection_), txt=str(x)) 

t = unstr(self.intersection2.__name__, tol=tol, **eps) 

raise IntersectionError(Fmt.no_convergence(d), txt=t) 

 

@property_RO 

def lat1(self): 

'''Get this rhumb line's latitude (C{degrees90}). 

''' 

return self._lat1 

 

@property_RO 

def lon1(self): 

'''Get this rhumb line's longitude (C{degrees180}). 

''' 

return self._lon1 

 

@Property_RO 

def latlon1(self): 

'''Get this rhumb line's lat- and longitude (L{LatLon2Tuple}C{(lat, lon)}). 

''' 

return LatLon2Tuple(self.lat1, self.lon1) 

 

@Property_RO 

def _mu1(self): 

'''(INTERNAL) Get the I{rectifying auxiliary} latitude C{mu} (C{degrees}). 

''' 

return self.ellipsoid.auxRectifying(self.lat1) 

 

def nearestOn4(self, lat, lon, tol=_TOL, **eps): 

'''Iteratively locate the point on this rhumb line nearest to 

the given point. 

 

@arg lat: Latitude of the point (C{degrees}). 

@arg lon: Longitude of the point (C{degrees}). 

@kwarg tol: Longitudinal convergence tolerance (C{degrees}). 

@kwarg eps: Tolerance for L{intersection3d3} (C{EPS}). 

 

@return: A L{NearestOn4Tuple}C{(lat, lon, distance, normal)} with 

the C{lat}- and C{lon}gitude of the nearest point on and 

the C{distance} in C{meter} to this rhumb line and with the 

azimuth of the C{normal}, perpendicular to this rhumb line. 

 

@raise IntersectionError: No convergence for this B{C{eps}} or 

no intersection for an other reason. 

 

@see: Methods L{RhumbLine.distance2} and L{RhumbLine.intersection2} 

and function L{intersection3d3}. 

''' 

z = _norm180(self.azi12 + _90_0) # perpendicular 

r = _RhumbLine(self.rhumb, lat, lon, z, caps=Caps.LINE_OFF) 

p = self.intersection2(r, tol=tol, **eps) 

t = r.distance2(p.lat, p.lon) 

return NearestOn4Tuple(p.lat, p.lon, t.distance, z, 

iteration=p.iteration) 

 

@Property_RO 

def _psi1(self): 

'''(INTERNAL) Get the I{isometric auxiliary} latitude C{psi} (C{degrees}). 

''' 

return self.ellipsoid.auxIsometric(self.lat1) 

 

@property_RO 

def RAorder(self): 

'''Get this rhumb line's I{Rhumb Area} order (C{int}, 4, 5, 6, 7 or 8). 

''' 

return self.rhumb.RAorder 

 

@Property_RO 

def _r1rad(self): # PYCHOK no cover 

'''(INTERNAL) Get this rhumb line's parallel I{circle radius} (C{meter}). 

''' 

return radians(self.ellipsoid.circle4(self.lat1).radius) 

 

@Property_RO 

def rhumb(self): 

'''Get this rhumb line's rhumb (L{Rhumb}). 

''' 

return self._rhumb 

 

def Position(self, s12, outmask=Caps.LATITUDE_LONGITUDE): 

'''Compute a position at a distance on this rhumb line. 

 

@arg s12: The distance along this rhumb between its point and 

the other point (C{meters}), can be negative. 

@kwarg outmask: Bit-or'ed combination of L{Caps} values specifying 

the quantities to be returned. 

 

@return: L{GDict} with 4 to 8 items C{azi12, a12, s12, S12, lat2, 

lon2, lat1, lon1} with latitude C{lat2} and longitude 

C{lon2} of the other point in C{degrees}, the rhumb angle 

C{a12} between both points in C{degrees} and the area C{S12} 

under the rhumb line in C{meter} I{squared}. 

 

@note: If B{C{s12}} is large enough that the rhumb line crosses a 

pole, the longitude of the second point is indeterminate and 

C{NAN} is returned for C{lon2} and area C{S12}. 

 

If the first point is a pole, the cosine of its latitude is 

taken to be C{epsilon}**-2 (where C{epsilon} is 2**-52). 

This position is extremely close to the actual pole and 

allows the calculation to be carried out in finite terms. 

''' 

r = GDict(name=self.name) 

if (outmask & Caps.LATITUDE_LONGITUDE_AREA): 

E, R = self.ellipsoid, self.rhumb 

mu12 = s12 * self._calp / E._L_90 

mu2 = mu12 + self._mu1 

if fabs(mu2) > 90: # PYCHOK no cover 

mu2 = _norm180(mu2) # reduce to [-180, 180) 

if fabs(mu2) > 90: # point on anti-meridian 

mu2 = _norm180(_180_0 - mu2) 

lat2x = E.auxRectifying(mu2, inverse=True) 

lon2x = NAN 

if (outmask & Caps.AREA): 

r.set_(S12=NAN) 

else: 

psi2 = self._psi1 

if self._calp: 

lat2x = E.auxRectifying(mu2, inverse=True) 

psi12 = R._DRectifying2Isometricd(mu2, 

self._mu1) * mu12 

lon2x = psi12 * self._salp / self._calp 

psi2 += psi12 

else: # PYCHOK no cover 

lat2x = self.lat1 

lon2x = self._salp * s12 / self._r1rad 

if (outmask & Caps.AREA): 

r.set_(S12=R._S12d(lon2x, self._psi1, psi2)) 

r.set_(s12=s12, azi12=self.azi12, a12=s12 / E._L_90) 

if (outmask & Caps.LATITUDE): 

r.set_(lat2=lat2x, lat1=self.lat1) 

if (outmask & Caps.LONGITUDE): 

if (outmask & Caps.LONG_UNROLL) and not isnan(lat2x): 

lon2x += self.lon1 

else: 

lon2x = _norm180(_norm180(self.lon1) + lon2x) 

r.set_(lon2=lon2x, lon1=self.lon1) 

if ((outmask | self._debug) & Caps._DEBUG_DIRECT_LINE): # PYCHOK no cover 

r.set_(a=E.a, f=E.f, f1=E.f1, L=E.L, exact=R.exact, 

b=E.b, e=E.e, e2=E.e2, k2=R._eF.k2, 

calp=self._calp, mu1 =self._mu1, mu12=mu12, 

salp=self._salp, psi1=self._psi1, mu2=mu2) 

return r 

 

def toStr(self, prec=6, sep=_COMMASPACE_, **unused): # PYCHOK signature 

'''Return this C{RhumbLine} as string. 

 

@kwarg prec: The C{float} precision, number of decimal digits (0..9). 

Trailing zero decimals are stripped for B{C{prec}} values 

of 1 and above, but kept for negative B{C{prec}} values. 

@kwarg sep: Separator to join (C{str}). 

 

@return: C{RhumbLine} (C{str}). 

''' 

d = dict(rhumb=self.rhumb, lat1=self.lat1, lon1=self.lon1, 

azi12=self.azi12, exact=self.exact, 

TMorder=self.TMorder, xTM=self.xTM) 

return sep.join(pairs(itemsorted(d, asorted=False), prec=prec)) 

 

@property_RO 

def TMorder(self): 

'''Get this rhumb line's I{Transverse Mercator} order (C{int}, 4, 5, 6, 7 or 8). 

''' 

return self.rhumb.TMorder 

 

@Property_RO 

def xTM(self): 

'''Get this rhumb line's I{Transverse Mercator} projection (L{ExactTransverseMercator} 

if I{exact} and I{ellipsoidal}, otherwise L{KTransverseMercator}). 

''' 

E = self.ellipsoid 

# ExactTransverseMercator doesn't handle spherical earth models 

return _MODS.etm.ExactTransverseMercator(E) if self.exact and E.isEllipsoidal else \ 

KTransverseMercator(E, TMorder=self.TMorder) 

 

def _xTM3d(self, latlon0, z=INT0, V3d=Vector3d): 

'''(INTERNAL) C{xTM.forward} this C{latlon1} to C{V3d} with B{C{latlon0}} 

as current intersection estimate and central meridian. 

''' 

t = self.xTM.forward(self.lat1 - latlon0.lat, self.lon1, lon0=latlon0.lon) 

return V3d(t.easting, t.northing, z) 

 

 

class RhumbLine(_RhumbLine): 

'''Compute one or several points on a single rhumb line. 

 

Class L{RhumbLine} facilitates the determination of points on 

a single rhumb line. The starting point (C{lat1}, C{lon1}) 

and the azimuth C{azi12} are specified once. 

 

Method L{RhumbLine.Position} returns the location of an other 

point and optionally the distance C{s12} along the corresponding 

area C{S12} under the rhumb line. 

 

Method L{RhumbLine.intersection2} finds the intersection between 

two rhumb lines. 

 

Method L{RhumbLine.nearestOn4} computes the nearest point on and 

its distance to a rhumb line. 

''' 

def __init__(self, rhumb, lat1=0, lon1=0, azi12=None, caps=0, name=NN): # case=Caps.? 

'''New L{RhumbLine}. 

 

@arg rhumb: The rhumb reference (L{Rhumb}). 

@kwarg lat1: Latitude of the start point (C{degrees90}). 

@kwarg lon1: Longitude of the start point (C{degrees180}). 

@kwarg azi12: Azimuth of this rhumb line (compass C{degrees}). 

@kwarg caps: Bit-or'ed combination of L{Caps} values specifying 

the capabilities. Include C{Caps.LINE_OFF} if 

updates to B{C{rhumb}} should I{not} be reflected 

in this rhumb line. 

@kwarg name: Optional name (C{str}). 

''' 

if (caps & Caps.LINE_OFF): # copy to avoid updates 

rhumb = rhumb.copy(deep=False, name=_under_name(rhumb.name)) 

_RhumbLine.__init__(self, rhumb, lat1, lon1, azi12, caps=caps, name=name) 

 

 

class RhumbOrder2Tuple(_GTuple): 

'''2-Tuple C{(RAorder, TMorder)} with a I{Rhumb Area} and 

I{Transverse Mercator} order, both C{int}. 

''' 

_Names_ = (Rhumb.RAorder.name, Rhumb.TMorder.name) 

_Units_ = ( Int, Int) 

 

 

class Rhumb8Tuple(_GTuple): 

'''8-Tuple C{(lat1, lon1, lat2, lon2, azi12, s12, S12, a12)} with lat- C{lat1}, 

C{lat2} and longitudes C{lon1}, C{lon2} of both points, the azimuth of the 

rhumb line C{azi12}, the distance C{s12}, the area C{S12} under the rhumb 

line and the angular distance C{a12} between both points. 

''' 

_Names_ = (_lat1_, _lon1_, _lat2_, _lon2_, _azi12_, _s12_, _S12_, _a12_) 

_Units_ = (_Lat, _Lon, _Lat, _Lon, _Azi, _M, _M2, _Deg) 

 

def toDirect9Tuple(self, dflt=NAN, **a12_azi1_azi2_m12_M12_M21): 

'''Convert this L{Rhumb8Tuple} result to a 9-tuple, like I{Karney}'s 

method C{geographiclib.geodesic.Geodesic._GenDirect}. 

 

@kwarg dflt: Default value for missing items (C{any}). 

@kwarg a12_azi1_azi2_m12_M12_M21: Optional keyword arguments 

to specify or override L{Inverse10Tuple} items. 

 

@return: L{Direct9Tuple}C{(a12, lat2, lon2, azi2, s12, 

m12, M12, M21, S12)} 

''' 

d = dict(azi1=self.azi12, M12=_1_0, m12=self.s12, # PYCHOK attr 

azi2=self.azi12, M21=_1_0) # PYCHOK attr 

if a12_azi1_azi2_m12_M12_M21: 

d.update(a12_azi1_azi2_m12_M12_M21) 

return self._toTuple(Direct9Tuple, dflt, d) 

 

def toInverse10Tuple(self, dflt=NAN, **a12_m12_M12_M21_salp1_calp1_salp2_calp2): 

'''Convert this L{Rhumb8Tuple} to a 10-tuple, like I{Karney}'s 

method C{geographiclib.geodesic.Geodesic._GenInverse}. 

 

@kwarg dflt: Default value for missing items (C{any}). 

@kwarg a12_m12_M12_M21_salp1_calp1_salp2_calp2: Optional keyword 

arguments to specify or override L{Inverse10Tuple} items. 

 

@return: L{Inverse10Tuple}C{(a12, s12, salp1, calp1, salp2, calp2, 

m12, M12, M21, S12)}. 

''' 

s, c = sincos2d(self.azi12) # PYCHOK attr 

d = dict(salp1=s, calp1=c, M12=_1_0, m12=self.s12, # PYCHOK attr 

salp2=s, calp2=c, M21=_1_0) 

if a12_m12_M12_M21_salp1_calp1_salp2_calp2: 

d.update(a12_m12_M12_M21_salp1_calp1_salp2_calp2) 

return self._toTuple(Inverse10Tuple, dflt, d) 

 

def _toTuple(self, nTuple, dflt, updates={}): 

'''(INTERNAL) Convert this C{Rhumb8Tuple} to an B{C{nTuple}}. 

''' 

_g = self.toGDict(**updates).get 

t = tuple(_g(n, dflt) for n in nTuple._Names_) 

return nTuple(t, name=self.name) 

 

@deprecated_method 

def _to7Tuple(self): 

'''DEPRECATED, do not use! 

''' 

return _MODS.deprecated.Rhumb7Tuple(self[:-1]) 

 

 

# Use I{Divided Differences} to determine (mu2 - mu1) / (psi2 - psi1) accurately. 

# Definition: _Df(x,y,d) = (f(x) - f(y)) / (x - y), @see W. M. Kahan & R. J. 

# Fateman, "Symbolic computation of Divided Differences", SIGSAM Bull. 33(3), 

# 7-28 (1999). U{ACM<https://DL.ACM.org/doi/pdf/10.1145/334714.334716>, @see 

# U{UCB<https://www.CS.Berkeley.edu/~fateman/papers/divdiff.pdf>}, Dec 8, 1999. 

 

def _Dasinh(x, y): 

hx = hypot1(x) 

d = x - y 

if d: 

hx *= y 

hy = x * hypot1(y) 

t = (d * (x + y) / (hy + hx)) if (x * y) > 0 else (hy - hx) 

r = asinh(t) / d 

else: 

r = _1_0 / hx 

return r 

 

 

def _Datan(x, y): 

xy = x * y 

r = xy + _1_0 

d = x - y 

if d: # 2 * xy > -1 == 2 * xy + 1 > 0 == xy + r > 0 == xy > -r 

r = (atan(d / r) if xy > -r else (atan(x) - atan(y))) / d 

else: 

r = _1_0 / r 

return r 

 

 

def _Dcosh(x, y): 

return _Dsincos(x, y, sinh, sinh) 

 

 

def _DeatanhE(x, y, E): 

# Deatanhe(x, y) = eatanhe((x - y) / (1 - e^2 * x * y)) / (x - y) 

e = _1_0 - E.e2 * x * y 

# assert not isnear0(e) 

d = x - y 

return (E._es_atanh(d / e) / d) if d else (E.e2 / e) 

 

 

def _DfEt(tx, ty, eF): # tangents 

# eF = Elliptic(-E.e12) # -E.e2 / (1 - E.e2) 

r, x, y, = _1_0, atan(tx), atan(ty) 

d = x - y 

if (x * y) > 0: 

# See U{DLMF<https://DLMF.NIST.gov/19.11>}: 19.11.2 and 19.11.4 

# letting theta -> x, phi -> -y, psi -> z 

# (E(x) - E(y)) / d = E(z)/d - k2 * sin(x) * sin(y) * sin(z)/d 

# tan(z/2) = (sin(x)*Delta(y) - sin(y)*Delta(x)) / (cos(x) + cos(y)) 

# = d * Dsin(x,y) * (sin(x) + sin(y))/(cos(x) + cos(y)) / 

# (sin(x)*Delta(y) + sin(y)*Delta(x)) 

# = t = d * Dt 

# sin(z) = 2*t/(1+t^2); cos(z) = (1-t^2)/(1+t^2) 

# Alt (this only works for |z| <= pi/2 -- however, this conditions 

# holds if x*y > 0): 

# sin(z) = d * Dsin(x,y) * (sin(x) + sin(y)) / 

# (sin(x)*cos(y)*Delta(y) + sin(y)*cos(x)*Delta(x)) 

# cos(z) = sqrt((1-sin(z))*(1+sin(z))) 

sx, cx, sy, cy = sincos2_(x, y) 

D = (cx + cy) * (eF.fDelta(sy, cy) * sx + 

eF.fDelta(sx, cx) * sy) 

D = (sx + sy) * _Dsin(x, y) / D 

t = D * d 

t2 = t**2 + _1_0 

D *= _2_0 / t2 

s = D * d 

if s: 

c = (t + _1_0) * (_1_0 - t) / t2 

r = eF.fE(s, c, eF.fDelta(s, c)) / s 

r = D * (r - eF.k2 * sx * sy) 

elif d: 

r = (eF.fE(x) - eF.fE(y)) / d 

return r 

 

 

def _Dgd(x, y): 

return _Datan(sinh(x), sinh(y)) * _Dsinh(x, y) 

 

 

def _Dgdinv(x, y): # x, y are tangents 

return _Dasinh(x, y) / _Datan(x, y) 

 

 

def _Dlog(x, y): 

d = (x - y) / _2_0 

# Changed atanh(t / (x + y)) to asinh(t / (2 * sqrt(x*y))) to 

# avoid taking atanh(1) when x is large and y is 1. This also 

# fixes bogus results being returned for the area when an endpoint 

# is at a pole. N.B. this routine is invoked with positive x 

# and y, so the sqrt is always taken of a positive quantity. 

return (asinh(d / sqrt(x * y)) / d) if d else (_1_0 / x) 

 

 

def _Dsin(x, y): 

return _Dsincos(x, y, sin, cos) 

 

 

def _Dsincos(x, y, sin_, cos_): 

r = cos_((x + y) * _0_5) 

d = (x - y) * _0_5 

if d: 

r *= sin_(d) / d 

return r 

 

 

def _Dsinh(x, y): 

return _Dsincos(x, y, sinh, cosh) 

 

 

def _Dtan(x, y): # PYCHOK no cover 

return _Dtant(x - y, tan(x), tan(y)) 

 

 

def _Dtant(dxy, tx, ty): 

txy = tx * ty 

r = txy + _1_0 

if dxy: # 2 * txy > -1 == 2 * txy + 1 > 0 == txy + r > 0 == txy > -r 

r = ((tan(dxy) * r) if txy > -r else (tx - ty)) / dxy 

return r 

 

 

def _Eaux4(E_aux, mu_psi_x, mu_psi_y): # degrees 

# get inverse auxiliary lats in radians and tangents 

phix = radians(E_aux(mu_psi_x, inverse=True)) 

phiy = radians(E_aux(mu_psi_y, inverse=True)) 

return phix, phiy, tan(phix), tan(phiy) 

 

 

def _gd(x): 

return atan(sinh(x)) 

 

 

def _sincosSeries(sinp, x, y, C, n): 

# N.B. C[] has n+1 elements of which 

# C[0] is ignored and n >= 0 

# Use Clenshaw summation to evaluate 

# m = (g(x) + g(y)) / 2 -- mean value 

# s = (g(x) - g(y)) / (x - y) -- average slope 

# where 

# g(x) = sum(C[j] * SC(2 * j * x), j = 1..n) 

# SC = sinp ? sin : cos 

# CS = sinp ? cos : sin 

# ... 

d = x - y 

sp, cp, sd, cd = sincos2_(x + y, d) 

sd = (sd / d) if d else _1_0 

m = cp * cd * _2_0 

s = neg(sp * sd) # negative 

# 2x2 matrices in row-major order 

a0, a1 = m, (s * d**2) 

a2, a3 = (s * _4_0), m 

b2 = b1 = _0_0s(4) 

if n > 0: 

b1 = C[n], _0_0, _0_0, C[n] 

_fsum1_, _neg = fsum1_, neg 

for j in range(n - 1, 0, -1): 

b1, b2, Cj = b2, b1, C[j] # C[0] unused 

# b1 = a * b2 - b1 + C[j] * I 

m0, m1, m2, m3 = b2 

n0, n1, n2, n3 = map(_neg, b1) 

b1 = (_fsum1_(a0 * m0, a1 * m2, n0, Cj, floats=True), 

_fsum1_(a0 * m1, a1 * m3, n1, floats=True), 

_fsum1_(a2 * m0, a3 * m2, n2, floats=True), 

_fsum1_(a2 * m1, a3 * m3, n3, Cj, floats=True)) 

# Here are the full expressions for m and s 

# f01, f02, f11, f12 = (0, 0, cd * sp, 2 * sd * cp) if sinp else \ 

# (1, 0, cd * cp, -2 * sd * sp) 

# m = -b2[1] * f02 + (C[0] - b2[0]) * f01 + b1[0] * f11 + b1[1] * f12 

# s = -b2[2] * f01 + (C[0] - b2[3]) * f02 + b1[2] * f11 + b1[3] * f12 

cd *= b1[2] 

sd *= b1[3] * _2_0 

s = _fsum1_(cd * sp, sd * cp, floats=True) if sinp else \ 

_fsum1_(cd * cp, _neg(sd * sp), _neg(b2[2]), floats=True) 

return s 

 

 

_RACoeffs = { # Generated by Maxima on 2015-05-15 08:24:04-04:00 

4: ( # GEOGRAPHICLIB_RHUMBAREA_ORDER == 4 

691, 7860, -20160, 18900, 0, 56700, # R[0]/n^0, polynomial(n), order 4 

1772, -5340, 6930, -4725, 14175, # R[1]/n^1, polynomial(n), order 3 

-1747, 1590, -630, 4725, # PYCHOK R[2]/n^2, polynomial(n), order 2 

104, -31, 315, # R[3]/n^3, polynomial(n), order 1 

-41, 420), # PYCHOK R[4]/n^4, polynomial(n), order 0, count = 20 

5: ( # GEOGRAPHICLIB_RHUMBAREA_ORDER == 5 

-79036, 22803, 259380, -665280, 623700, 0, 1871100, # PYCHOK R[0]/n^0, polynomial(n), order 5 

41662, 58476, -176220, 228690, -155925, 467775, # PYCHOK R[1]/n^1, polynomial(n), order 4 

18118, -57651, 52470, -20790, 155925, # PYCHOK R[2]/n^2, polynomial(n), order 3 

-23011, 17160, -5115, 51975, # PYCHOK R[3]/n^3, polynomial(n), order 2 

5480, -1353, 13860, # PYCHOK R[4]/n^4, polynomial(n), order 1 

-668, 5775), # PYCHOK R[5]/n^5, polynomial(n), order 0, count = 27 

6: ( # GEOGRAPHICLIB_RHUMBAREA_ORDER == 6 

128346268, -107884140, 31126095, 354053700, -908107200, 851350500, 0, 2554051500, # R[0]/n^0, polynomial(n), order 6 

-114456994, 56868630, 79819740, -240540300, 312161850, -212837625, 638512875, # PYCHOK R[1]/n^1, polynomial(n), order 5 

51304574, 24731070, -78693615, 71621550, -28378350, 212837625, # R[2]/n^2, polynomial(n), order 4 

1554472, -6282003, 4684680, -1396395, 14189175, # R[3]/n^3, polynomial(n), order 3 

-4913956, 3205800, -791505, 8108100, # PYCHOK R[4]/n^4, polynomial(n), order 2 

1092376, -234468, 2027025, # R[5]/n^5, polynomial(n), order 1 

-313076, 2027025), # PYCHOK R[6]/n^6, polynomial(n), order 0, count = 35 

7: ( # GEOGRAPHICLIB_RHUMBAREA_ORDER == 7 

-317195588, 385038804, -323652420, 93378285, 1062161100, -2724321600, 2554051500, 0, 7662154500, # PYCHOK R[0]/n^0, polynomial(n), order 7 

258618446, -343370982, 170605890, 239459220, -721620900, 936485550, -638512875, 1915538625, # PYCHOK R[1]/n^1, polynomial(n), order 6 

-248174686, 153913722, 74193210, -236080845, 214864650, -85135050, 638512875, # PYCHOK R[2]/n^2, polynomial(n), order 5 

114450437, 23317080, -94230045, 70270200, -20945925, 212837625, # PYCHOK R[3]/n^3, polynomial(n), order 4 

15445736, -103193076, 67321800, -16621605, 170270100, # PYCHOK R[4]/n^4, polynomial(n), order 3 

-27766753, 16385640, -3517020, 30405375, # PYCHOK R[4]/n^4, polynomial(n), order 3 

4892722, -939228, 6081075, # PYCHOK R[4]/n^4, polynomial(n), order 3 

-3189007, 14189175), # PYCHOK R[7]/n^7, polynomial(n), order 0, count = 44 

8: ( # GEOGRAPHICLIB_RHUMBAREA_ORDER == 8 

71374704821, -161769749880, 196369790040, -165062734200, 47622925350, 541702161000, -1389404016000, 1302566265000, 0, 3907698795000, # R[0]/n^0, polynomial(n), order 8 

-13691187484, 65947703730, -87559600410, 43504501950, 61062101100, -184013329500, 238803815250, -162820783125, 488462349375, # PYCHOK R[1]/n^1, polynomial(n), order 7 

30802104839, -63284544930, 39247999110, 18919268550, -60200615475, 54790485750, -21709437750, 162820783125, # R[2]/n^2, polynomial(n), order 6 

-8934064508, 5836972287, 1189171080, -4805732295, 3583780200, -1068242175, 10854718875, # PYCHOK R[3]/n^3, polynomial(n), order 5 

50072287748, 3938662680, -26314234380, 17167059000, -4238509275, 43418875500, # R[4]/n^4, polynomial(n), order 4 

359094172, -9912730821, 5849673480, -1255576140, 10854718875, # R[5]/n^5, polynomial(n), order 3 

-16053944387, 8733508770, -1676521980, 10854718875, # PYCHOK R[6]/n^6, polynomial(n), order 2 

930092876, -162639357, 723647925, # R[7]/n^7, polynomial(n), order 1 

-673429061, 1929727800) # PYCHOK R[8]/n^8, polynomial(n), order 0, count = 54 

} 

 

__all__ += _ALL_DOCS(Caps, _RhumbLine) 

 

if __name__ == '__main__': 

 

def _re(fmt, r3, x3): 

e3 = [] 

for r, x in _zip(r3, x3): # strict=True 

e = abs(r - x) / abs(x) 

e3.append('%.g' % (e,)) 

print((fmt % r3) + ' rel errors: ' + ', '.join(e3)) 

 

# <https://GeographicLib.SourceForge.io/cgi-bin/RhumbSolve> 

rhumb = Rhumb(exact=True) # WGS84 default 

print('# %r\n' % rhumb) 

r = rhumb.Direct8(40.6, -73.8, 51, 5.5e6) # from JFK about NE 

_re('# JFK NE lat2=%.8f, lon2=%.8f, S12=%.1f', (r.lat2, r.lon2, r.S12), (71.68889988, 0.25551982, 44095641862956.148438)) 

r = rhumb.Inverse8(40.6, -73.8, 51.6, -0.5) # JFK to LHR 

_re('# JFK-LHR azi12=%.8f, s12=%.3f S12=%.1f', (r.azi12, r.s12, r.S12), (77.76838971, 5771083.383328, 37395209100030.367188)) 

r = rhumb.Inverse8(40.6, -73.8, 35.8, 140.3) # JFK to Tokyo Narita 

_re('# JFK-NRT azi12=%.8f, s12=%.3f S12=%.1f', (r.azi12, r.s12, r.S12), (-92.388887981699639, 12782581.0676841792, -63760642939072.492)) 

 

# % python3 -m pygeodesy.rhumbx 

 

# Rhumb(RAorder=6, TMorder=6, ellipsoid=Ellipsoid(name='WGS84', a=6378137, b=6356752.31424518, f_=298.25722356, f=0.00335281, f2=0.00336409, n=0.00167922, e=0.08181919, e2=0.00669438, e22=0.0067395, e32=0.00335843, A=6367449.14582341, L=10001965.72931272, R1=6371008.77141506, R2=6371007.18091847, R3=6371000.79000916, Rbiaxial=6367453.63451633, Rtriaxial=6372797.5559594), exact=True) 

 

# JFK NE lat2=71.68889988, lon2=0.25551982, S12=44095641862956.1 rel errors: 4e-11, 2e-08, 2e-15 

# JFK-LHR azi12=77.76838971, s12=5771083.383 S12=37395209100030.4 rel errors: 3e-12, 5e-15, 2e-16 

# JFK-NRT azi12=-92.38888798, s12=12782581.068 S12=-63760642939072.5 rel errors: 2e-16, 3e-16, 0 

 

# **) MIT License 

# 

# Copyright (C) 2022-2022 -- mrJean1 at Gmail -- All Rights Reserved. 

# 

# Permission is hereby granted, free of charge, to any person obtaining a 

# copy of this software and associated documentation files (the "Software"), 

# to deal in the Software without restriction, including without limitation 

# the rights to use, copy, modify, merge, publish, distribute, sublicense, 

# and/or sell copies of the Software, and to permit persons to whom the 

# Software is furnished to do so, subject to the following conditions: 

# 

# The above copyright notice and this permission notice shall be included 

# in all copies or substantial portions of the Software. 

# 

# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS 

# OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 

# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 

# THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR 

# OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, 

# ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR 

# OTHER DEALINGS IN THE SOFTWARE.