GeographicLib: CircularEngine.cpp Source File

GeographicLib 2.5.2

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CircularEngine.cpp
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1/**
2 * \file CircularEngine.cpp
3 * \brief Implementation for GeographicLib::CircularEngine class
4 *
5 * Copyright (c) Charles Karney (2011) <karney@alum.mit.edu> and licensed under
6 * the MIT/X11 License. For more information, see
7 * https://geographiclib.sourceforge.io/
8 **********************************************************************/
9
10#include <GeographicLib/CircularEngine.hpp>
11
12namespace GeographicLib {
13
14 using namespace std;
15
16 Math::real CircularEngine::Value(bool gradp, real sl, real cl,
17 real& gradx, real& grady, real& gradz) const
18 {
19 gradp = _gradp && gradp;
20 const vector<real>& root( SphericalEngine::sqrttable() );
21
22 // Initialize outer sum
23 real vc = 0, vc2 = 0, vs = 0, vs2 = 0; // v [N + 1], v [N + 2]
24 // vr, vt, vl and similar w variable accumulate the sums for the
25 // derivatives wrt r, theta, and lambda, respectively.
26 real vrc = 0, vrc2 = 0, vrs = 0, vrs2 = 0; // vr[N + 1], vr[N + 2]
27 real vtc = 0, vtc2 = 0, vts = 0, vts2 = 0; // vt[N + 1], vt[N + 2]
28 real vlc = 0, vlc2 = 0, vls = 0, vls2 = 0; // vl[N + 1], vl[N + 2]
29 for (int m = _mM; m >= 0; --m) { // m = M .. 0
30 // Now Sc[m] = wc, Ss[m] = ws
31 // Sc'[m] = wtc, Ss'[m] = wtc
32 if (m) {
33 real v, A, B; // alpha[m], beta[m + 1]
34 switch (_norm) {
35 case FULL:
36 v = root[2] * root[2 * m + 3] / root[m + 1];
37 A = cl * v * _uq;
38 B = - v * root[2 * m + 5] / (root[8] * root[m + 2]) * _uq2;
39 break;
40 case SCHMIDT:
41 v = root[2] * root[2 * m + 1] / root[m + 1];
42 A = cl * v * _uq;
43 B = - v * root[2 * m + 3] / (root[8] * root[m + 2]) * _uq2;
44 break;
45 default:
46 A = B = 0;
47 }
48 v = A * vc + B * vc2 + _wc[m] ; vc2 = vc ; vc = v;
49 v = A * vs + B * vs2 + _ws[m] ; vs2 = vs ; vs = v;
50 if (gradp) {
51 v = A * vrc + B * vrc2 + _wrc[m]; vrc2 = vrc; vrc = v;
52 v = A * vrs + B * vrs2 + _wrs[m]; vrs2 = vrs; vrs = v;
53 v = A * vtc + B * vtc2 + _wtc[m]; vtc2 = vtc; vtc = v;
54 v = A * vts + B * vts2 + _wts[m]; vts2 = vts; vts = v;
55 v = A * vlc + B * vlc2 + m*_ws[m]; vlc2 = vlc; vlc = v;
56 v = A * vls + B * vls2 - m*_wc[m]; vls2 = vls; vls = v;
57 }
58 } else {
59 real A, B, qs;
60 switch (_norm) {
61 case FULL:
62 A = root[3] * _uq; // F[1]/(q*cl) or F[1]/(q*sl)
63 B = - root[15]/2 * _uq2; // beta[1]/q
64 break;
65 case SCHMIDT:
66 A = _uq;
67 B = - root[3]/2 * _uq2;
68 break;
69 default:
70 A = B = 0;
71 }
72 qs = _q / SphericalEngine::scale();
73 vc = qs * (_wc[m] + A * (cl * vc + sl * vs ) + B * vc2);
74 if (gradp) {
75 qs /= _r;
76 // The components of the gradient in circular coordinates are
77 // r: dV/dr
78 // theta: 1/r * dV/dtheta
79 // lambda: 1/(r*u) * dV/dlambda
80 vrc = - qs * (_wrc[m] + A * (cl * vrc + sl * vrs) + B * vrc2);
81 vtc = qs * (_wtc[m] + A * (cl * vtc + sl * vts) + B * vtc2);
82 vlc = qs / _u * ( A * (cl * vlc + sl * vls) + B * vlc2);
83 }
84 }
85 }
86
87 if (gradp) {
88 // Rotate into cartesian (geocentric) coordinates
89 gradx = cl * (_u * vrc + _t * vtc) - sl * vlc;
90 grady = sl * (_u * vrc + _t * vtc) + cl * vlc;
91 gradz = _t * vrc - _u * vtc ;
92 }
93 return vc;
94 }
95
96} // namespace GeographicLib
CircularEngine.hpp
Header for GeographicLib::CircularEngine class.
real
GeographicLib::Math::real real
Definition GeodSolve.cpp:28
GeographicLib::Math::real
double real
Definition Math.hpp:115
GeographicLib
Namespace for GeographicLib.
Definition Accumulator.cpp:12