/src/proj/src/projections/omerc.cpp

Source (jump to first uncovered line)
/*
** Copyright (c) 2003, 2006   Gerald I. Evenden
*/
/*
** 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.
*/

#include <errno.h>
#include <math.h>

#include "proj.h"
#include "proj_internal.h"

PROJ_HEAD(omerc, "Oblique Mercator")
"\n\tCyl, Sph&Ell no_rot\n\t"
    "alpha= [gamma=] [no_off] lonc= or\n\t lon_1= lat_1= lon_2= lat_2=";

namespace { // anonymous namespace
struct pj_omerc_data {
    double A, B, E, AB, ArB, BrA, rB, singam, cosgam, sinrot, cosrot;
    double v_pole_n, v_pole_s, u_0;
    int no_rot;
};
} // anonymous namespace

#define TOL 1.e-7
#define EPS 1.e-10

static PJ_XY omerc_e_forward(PJ_LP lp, PJ *P) { /* Ellipsoidal, forward */
    PJ_XY xy = {0.0, 0.0};
    struct pj_omerc_data *Q = static_cast<struct pj_omerc_data *>(P->opaque);
    double u, v;

    if (fabs(fabs(lp.phi) - M_HALFPI) > EPS) {
        const double W = Q->E / pow(pj_tsfn(lp.phi, sin(lp.phi), P->e), Q->B);
        const double one_div_W = 1. / W;
        const double S = .5 * (W - one_div_W);
        const double T = .5 * (W + one_div_W);
        const double V = sin(Q->B * lp.lam);
        const double U = (S * Q->singam - V * Q->cosgam) / T;
        if (fabs(fabs(U) - 1.0) < EPS) {
            proj_errno_set(P, PROJ_ERR_COORD_TRANSFM_OUTSIDE_PROJECTION_DOMAIN);
            return xy;
        }
        v = 0.5 * Q->ArB * log((1. - U) / (1. + U));
        const double temp = cos(Q->B * lp.lam);
        if (fabs(temp) < TOL) {
            u = Q->A * lp.lam;
        } else {
            u = Q->ArB * atan2((S * Q->cosgam + V * Q->singam), temp);
        }
    } else {
        v = lp.phi > 0 ? Q->v_pole_n : Q->v_pole_s;
        u = Q->ArB * lp.phi;
    }
    if (Q->no_rot) {
        xy.x = u;
        xy.y = v;
    } else {
        u -= Q->u_0;
        xy.x = v * Q->cosrot + u * Q->sinrot;
        xy.y = u * Q->cosrot - v * Q->sinrot;
    }
    return xy;
}

static PJ_LP omerc_e_inverse(PJ_XY xy, PJ *P) { /* Ellipsoidal, inverse */
    PJ_LP lp = {0.0, 0.0};
    struct pj_omerc_data *Q = static_cast<struct pj_omerc_data *>(P->opaque);
    double u, v, Qp, Sp, Tp, Vp, Up;

    if (Q->no_rot) {
        v = xy.y;
        u = xy.x;
    } else {
        v = xy.x * Q->cosrot - xy.y * Q->sinrot;
        u = xy.y * Q->cosrot + xy.x * Q->sinrot + Q->u_0;
    }
    Qp = exp(-Q->BrA * v);
    if (Qp == 0) {
        proj_errno_set(P, PROJ_ERR_COORD_TRANSFM_OUTSIDE_PROJECTION_DOMAIN);
        return proj_coord_error().lp;
    }
    Sp = .5 * (Qp - 1. / Qp);
    Tp = .5 * (Qp + 1. / Qp);
    Vp = sin(Q->BrA * u);
    Up = (Vp * Q->cosgam + Sp * Q->singam) / Tp;
    if (fabs(fabs(Up) - 1.) < EPS) {
        lp.lam = 0.;
        lp.phi = Up < 0. ? -M_HALFPI : M_HALFPI;
    } else {
        lp.phi = Q->E / sqrt((1. + Up) / (1. - Up));
        if ((lp.phi = pj_phi2(P->ctx, pow(lp.phi, 1. / Q->B), P->e)) ==
            HUGE_VAL) {
            proj_errno_set(P, PROJ_ERR_COORD_TRANSFM_OUTSIDE_PROJECTION_DOMAIN);
            return lp;
        }
        lp.lam =
            -Q->rB * atan2((Sp * Q->cosgam - Vp * Q->singam), cos(Q->BrA * u));
    }
    return lp;
}

PJ *PJ_PROJECTION(omerc) {
    double con, com, cosph0, D, F, H, L, sinph0, p, J,
        gamma = 0, gamma0, lamc = 0, lam1 = 0, lam2 = 0, phi1 = 0, phi2 = 0,
        alpha_c = 0;
    int alp, gam, no_off = 0;

    struct pj_omerc_data *Q = static_cast<struct pj_omerc_data *>(
        calloc(1, sizeof(struct pj_omerc_data)));
    if (nullptr == Q)
        return pj_default_destructor(P, PROJ_ERR_OTHER /*ENOMEM*/);
    P->opaque = Q;

    Q->no_rot = pj_param(P->ctx, P->params, "bno_rot").i;
    if ((alp = pj_param(P->ctx, P->params, "talpha").i) != 0)
        alpha_c = pj_param(P->ctx, P->params, "ralpha").f;
    if ((gam = pj_param(P->ctx, P->params, "tgamma").i) != 0)
        gamma = pj_param(P->ctx, P->params, "rgamma").f;
    if (alp || gam) {
        lamc = pj_param(P->ctx, P->params, "rlonc").f;
        no_off =
            /* For libproj4 compatibility */
            pj_param(P->ctx, P->params, "tno_off").i
            /* for backward compatibility */
            || pj_param(P->ctx, P->params, "tno_uoff").i;
        if (no_off) {
            /* Mark the parameter as used, so that the pj_get_def() return them
             */
            pj_param(P->ctx, P->params, "sno_uoff");
            pj_param(P->ctx, P->params, "sno_off");
        }
    } else {
        lam1 = pj_param(P->ctx, P->params, "rlon_1").f;
        phi1 = pj_param(P->ctx, P->params, "rlat_1").f;
        lam2 = pj_param(P->ctx, P->params, "rlon_2").f;
        phi2 = pj_param(P->ctx, P->params, "rlat_2").f;
        con = fabs(phi1);

        if (fabs(phi1) > M_HALFPI - TOL) {
            proj_log_error(
                P, _("Invalid value for lat_1: |lat_1| should be < 90°"));
            return pj_default_destructor(P,
                                         PROJ_ERR_INVALID_OP_ILLEGAL_ARG_VALUE);
        }
        if (fabs(phi2) > M_HALFPI - TOL) {
            proj_log_error(
                P, _("Invalid value for lat_2: |lat_2| should be < 90°"));
            return pj_default_destructor(P,
                                         PROJ_ERR_INVALID_OP_ILLEGAL_ARG_VALUE);
        }

        if (fabs(phi1 - phi2) <= TOL) {
            proj_log_error(P,
                           _("Invalid value for lat_1/lat_2: lat_1 should be "
                             "different from lat_2"));
            return pj_default_destructor(P,
                                         PROJ_ERR_INVALID_OP_ILLEGAL_ARG_VALUE);
        }

        if (con <= TOL) {
            proj_log_error(
                P,
                _("Invalid value for lat_1: lat_1 should be different from 0"));
            return pj_default_destructor(P,
                                         PROJ_ERR_INVALID_OP_ILLEGAL_ARG_VALUE);
        }

        if (fabs(fabs(P->phi0) - M_HALFPI) <= TOL) {
            proj_log_error(
                P, _("Invalid value for lat_0: |lat_0| should be < 90°"));
            return pj_default_destructor(P,
                                         PROJ_ERR_INVALID_OP_ILLEGAL_ARG_VALUE);
        }
    }

    if (pj_param(P->ctx, P->params, "rlon_0").i) {
        proj_log_trace(P, _("lon_0 is ignored."));
    }

    com = sqrt(P->one_es);
    if (fabs(P->phi0) > EPS) {
        sinph0 = sin(P->phi0);
        cosph0 = cos(P->phi0);
        con = 1. - P->es * sinph0 * sinph0;
        Q->B = cosph0 * cosph0;
        Q->B = sqrt(1. + P->es * Q->B * Q->B / P->one_es);
        Q->A = Q->B * P->k0 * com / con;
        D = Q->B * com / (cosph0 * sqrt(con));
        if ((F = D * D - 1.) <= 0.)
            F = 0.;
        else {
            F = sqrt(F);
            if (P->phi0 < 0.)
                F = -F;
        }
        Q->E = F += D;
        Q->E *= pow(pj_tsfn(P->phi0, sinph0, P->e), Q->B);
    } else {
        Q->B = 1. / com;
        Q->A = P->k0;
        Q->E = D = F = 1.;
    }
    if (alp || gam) {
        if (alp) {
            gamma0 = aasin(P->ctx, sin(alpha_c) / D);
            if (!gam)
                gamma = alpha_c;
        } else {
            gamma0 = gamma;
            alpha_c = aasin(P->ctx, D * sin(gamma0));
            if (proj_errno(P) != 0) {
                // For a sphere, |gamma| must be <= 90 - |lat_0|
                // On an ellipsoid, this is very slightly above
                proj_log_error(P,
                               ("Invalid value for gamma: given lat_0 value, "
                                "|gamma| should be <= " +
                                std::to_string(asin(1. / D) / M_PI * 180) + "°")
                                   .c_str());
                return pj_default_destructor(
                    P, PROJ_ERR_INVALID_OP_ILLEGAL_ARG_VALUE);
            }
        }

        if (fabs(fabs(P->phi0) - M_HALFPI) <= TOL) {
            proj_log_error(
                P, _("Invalid value for lat_0: |lat_0| should be < 90°"));
            return pj_default_destructor(P,
                                         PROJ_ERR_INVALID_OP_ILLEGAL_ARG_VALUE);
        }

        P->lam0 = lamc - aasin(P->ctx, .5 * (F - 1. / F) * tan(gamma0)) / Q->B;
    } else {
        H = pow(pj_tsfn(phi1, sin(phi1), P->e), Q->B);
        L = pow(pj_tsfn(phi2, sin(phi2), P->e), Q->B);
        F = Q->E / H;
        p = (L - H) / (L + H);
        if (p == 0) {
            // Not quite, but es is very close to 1...
            proj_log_error(P, _("Invalid value for eccentricity"));
            return pj_default_destructor(P,
                                         PROJ_ERR_INVALID_OP_ILLEGAL_ARG_VALUE);
        }
        J = Q->E * Q->E;
        J = (J - L * H) / (J + L * H);
        if ((con = lam1 - lam2) < -M_PI)
            lam2 -= M_TWOPI;
        else if (con > M_PI)
            lam2 += M_TWOPI;
        P->lam0 = adjlon(.5 * (lam1 + lam2) -
                         atan(J * tan(.5 * Q->B * (lam1 - lam2)) / p) / Q->B);
        const double denom = F - 1. / F;
        if (denom == 0) {
            proj_log_error(P, _("Invalid value for eccentricity"));
            return pj_default_destructor(P,
                                         PROJ_ERR_INVALID_OP_ILLEGAL_ARG_VALUE);
        }
        gamma0 = atan(2. * sin(Q->B * adjlon(lam1 - P->lam0)) / denom);
        gamma = alpha_c = aasin(P->ctx, D * sin(gamma0));
    }
    Q->singam = sin(gamma0);
    Q->cosgam = cos(gamma0);
    Q->sinrot = sin(gamma);
    Q->cosrot = cos(gamma);
    Q->BrA = 1. / (Q->ArB = Q->A * (Q->rB = 1. / Q->B));
    Q->AB = Q->A * Q->B;
    if (no_off)
        Q->u_0 = 0;
    else {
        Q->u_0 = fabs(Q->ArB * atan(sqrt(D * D - 1.) / cos(alpha_c)));
        if (P->phi0 < 0.)
            Q->u_0 = -Q->u_0;
    }
    F = 0.5 * gamma0;
    Q->v_pole_n = Q->ArB * log(tan(M_FORTPI - F));
    Q->v_pole_s = Q->ArB * log(tan(M_FORTPI + F));
    P->inv = omerc_e_inverse;
    P->fwd = omerc_e_forward;

    return P;
}

#undef TOL
#undef EPS

Coverage Report

Created: 2025-06-13 06:29

Line	Count	Source (jump to first uncovered line)
1		/*
2		** Copyright (c) 2003, 2006 Gerald I. Evenden
3		*/
4		/*
5		** Permission is hereby granted, free of charge, to any person obtaining
6		** a copy of this software and associated documentation files (the
7		** "Software"), to deal in the Software without restriction, including
8		** without limitation the rights to use, copy, modify, merge, publish,
9		** distribute, sublicense, and/or sell copies of the Software, and to
10		** permit persons to whom the Software is furnished to do so, subject to
11		** the following conditions:
12		**
13		** The above copyright notice and this permission notice shall be
14		** included in all copies or substantial portions of the Software.
15		**
16		** THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
17		** EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
18		** MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
19		** IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
20		** CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
21		** TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
22		** SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
23		*/
24
25		#include <errno.h>
26		#include <math.h>
27
28		#include "proj.h"
29		#include "proj_internal.h"
30
31		PROJ_HEAD(omerc, "Oblique Mercator")
32		"\n\tCyl, Sph&Ell no_rot\n\t"
33		"alpha= [gamma=] [no_off] lonc= or\n\t lon_1= lat_1= lon_2= lat_2=";
34
35		namespace { // anonymous namespace
36		struct pj_omerc_data {
37		double A, B, E, AB, ArB, BrA, rB, singam, cosgam, sinrot, cosrot;
38		double v_pole_n, v_pole_s, u_0;
39		int no_rot;
40		};
41		} // anonymous namespace
42
43	2.42k	#define TOL 1.e-7
44	824	#define EPS 1.e-10
45
46	0	static PJ_XY omerc_e_forward(PJ_LP lp, PJ P) { / Ellipsoidal, forward */
47	0	PJ_XY xy = {0.0, 0.0};
48	0	struct pj_omerc_data Q = static_cast<struct pj_omerc_data >(P->opaque);
49	0	double u, v;
50
51	0	if (fabs(fabs(lp.phi) - M_HALFPI) > EPS) {
52	0	const double W = Q->E / pow(pj_tsfn(lp.phi, sin(lp.phi), P->e), Q->B);
53	0	const double one_div_W = 1. / W;
54	0	const double S = .5 * (W - one_div_W);
55	0	const double T = .5 * (W + one_div_W);
56	0	const double V = sin(Q->B * lp.lam);
57	0	const double U = (S * Q->singam - V * Q->cosgam) / T;
58	0	if (fabs(fabs(U) - 1.0) < EPS) {
59	0	proj_errno_set(P, PROJ_ERR_COORD_TRANSFM_OUTSIDE_PROJECTION_DOMAIN);
60	0	return xy;
61	0	}
62	0	v = 0.5 * Q->ArB * log((1. - U) / (1. + U));
63	0	const double temp = cos(Q->B * lp.lam);
64	0	if (fabs(temp) < TOL) {
65	0	u = Q->A * lp.lam;
66	0	} else {
67	0	u = Q->ArB * atan2((S * Q->cosgam + V * Q->singam), temp);
68	0	}
69	0	} else {
70	0	v = lp.phi > 0 ? Q->v_pole_n : Q->v_pole_s;
71	0	u = Q->ArB * lp.phi;
72	0	}
73	0	if (Q->no_rot) {
74	0	xy.x = u;
75	0	xy.y = v;
76	0	} else {
77	0	u -= Q->u_0;
78	0	xy.x = v * Q->cosrot + u * Q->sinrot;
79	0	xy.y = u * Q->cosrot - v * Q->sinrot;
80	0	}
81	0	return xy;
82	0	}
83
84	0	static PJ_LP omerc_e_inverse(PJ_XY xy, PJ P) { / Ellipsoidal, inverse */
85	0	PJ_LP lp = {0.0, 0.0};
86	0	struct pj_omerc_data Q = static_cast<struct pj_omerc_data >(P->opaque);
87	0	double u, v, Qp, Sp, Tp, Vp, Up;
88
89	0	if (Q->no_rot) {
90	0	v = xy.y;
91	0	u = xy.x;
92	0	} else {
93	0	v = xy.x * Q->cosrot - xy.y * Q->sinrot;
94	0	u = xy.y * Q->cosrot + xy.x * Q->sinrot + Q->u_0;
95	0	}
96	0	Qp = exp(-Q->BrA * v);
97	0	if (Qp == 0) {
98	0	proj_errno_set(P, PROJ_ERR_COORD_TRANSFM_OUTSIDE_PROJECTION_DOMAIN);
99	0	return proj_coord_error().lp;
100	0	}
101	0	Sp = .5 * (Qp - 1. / Qp);
102	0	Tp = .5 * (Qp + 1. / Qp);
103	0	Vp = sin(Q->BrA * u);
104	0	Up = (Vp * Q->cosgam + Sp * Q->singam) / Tp;
105	0	if (fabs(fabs(Up) - 1.) < EPS) {
106	0	lp.lam = 0.;
107	0	lp.phi = Up < 0. ? -M_HALFPI : M_HALFPI;
108	0	} else {
109	0	lp.phi = Q->E / sqrt((1. + Up) / (1. - Up));
110	0	if ((lp.phi = pj_phi2(P->ctx, pow(lp.phi, 1. / Q->B), P->e)) ==
111	0	HUGE_VAL) {
112	0	proj_errno_set(P, PROJ_ERR_COORD_TRANSFM_OUTSIDE_PROJECTION_DOMAIN);
113	0	return lp;
114	0	}
115	0	lp.lam =
116	0	-Q->rB * atan2((Sp * Q->cosgam - Vp * Q->singam), cos(Q->BrA * u));
117	0	}
118	0	return lp;
119	0	}
120
121	842	PJ *PJ_PROJECTION(omerc) {
122	842	double con, com, cosph0, D, F, H, L, sinph0, p, J,
123	842	gamma = 0, gamma0, lamc = 0, lam1 = 0, lam2 = 0, phi1 = 0, phi2 = 0,
124	842	alpha_c = 0;
125	842	int alp, gam, no_off = 0;
126
127	842	struct pj_omerc_data Q = static_cast<struct pj_omerc_data >(
128	842	calloc(1, sizeof(struct pj_omerc_data)));
129	842	if (nullptr == Q)
130	0	return pj_default_destructor(P, PROJ_ERR_OTHER /ENOMEM/);
131	842	P->opaque = Q;
132
133	842	Q->no_rot = pj_param(P->ctx, P->params, "bno_rot").i;
134	842	if ((alp = pj_param(P->ctx, P->params, "talpha").i) != 0)
135	384	alpha_c = pj_param(P->ctx, P->params, "ralpha").f;
136	842	if ((gam = pj_param(P->ctx, P->params, "tgamma").i) != 0)
137	154	gamma = pj_param(P->ctx, P->params, "rgamma").f;
138	842	if (alp \|\| gam) {
139	437	lamc = pj_param(P->ctx, P->params, "rlonc").f;
140	437	no_off =
141		/* For libproj4 compatibility */
142	437	pj_param(P->ctx, P->params, "tno_off").i
143		/* for backward compatibility */
144	437	\|\| pj_param(P->ctx, P->params, "tno_uoff").i;
145	437	if (no_off) {
146		/* Mark the parameter as used, so that the pj_get_def() return them
147		*/
148	74	pj_param(P->ctx, P->params, "sno_uoff");
149	74	pj_param(P->ctx, P->params, "sno_off");
150	74	}
151	437	} else {
152	405	lam1 = pj_param(P->ctx, P->params, "rlon_1").f;
153	405	phi1 = pj_param(P->ctx, P->params, "rlat_1").f;
154	405	lam2 = pj_param(P->ctx, P->params, "rlon_2").f;
155	405	phi2 = pj_param(P->ctx, P->params, "rlat_2").f;
156	405	con = fabs(phi1);
157
158	405	if (fabs(phi1) > M_HALFPI - TOL) {
159	3	proj_log_error(
160	3	P, _("Invalid value for lat_1: \|lat_1\| should be < 90°"));
161	3	return pj_default_destructor(P,
162	3	PROJ_ERR_INVALID_OP_ILLEGAL_ARG_VALUE);
163	3	}
164	402	if (fabs(phi2) > M_HALFPI - TOL) {
165	3	proj_log_error(
166	3	P, _("Invalid value for lat_2: \|lat_2\| should be < 90°"));
167	3	return pj_default_destructor(P,
168	3	PROJ_ERR_INVALID_OP_ILLEGAL_ARG_VALUE);
169	3	}
170
171	399	if (fabs(phi1 - phi2) <= TOL) {
172	7	proj_log_error(P,
173	7	_("Invalid value for lat_1/lat_2: lat_1 should be "
174	7	"different from lat_2"));
175	7	return pj_default_destructor(P,
176	7	PROJ_ERR_INVALID_OP_ILLEGAL_ARG_VALUE);
177	7	}
178
179	392	if (con <= TOL) {
180	4	proj_log_error(
181	4	P,
182	4	_("Invalid value for lat_1: lat_1 should be different from 0"));
183	4	return pj_default_destructor(P,
184	4	PROJ_ERR_INVALID_OP_ILLEGAL_ARG_VALUE);
185	4	}
186
187	388	if (fabs(fabs(P->phi0) - M_HALFPI) <= TOL) {
188	1	proj_log_error(
189	1	P, _("Invalid value for lat_0: \|lat_0\| should be < 90°"));
190	1	return pj_default_destructor(P,
191	1	PROJ_ERR_INVALID_OP_ILLEGAL_ARG_VALUE);
192	1	}
193	388	}
194
195	824	if (pj_param(P->ctx, P->params, "rlon_0").i) {
196	122	proj_log_trace(P, _("lon_0 is ignored."));
197	122	}
198
199	824	com = sqrt(P->one_es);
200	824	if (fabs(P->phi0) > EPS) {
201	174	sinph0 = sin(P->phi0);
202	174	cosph0 = cos(P->phi0);
203	174	con = 1. - P->es * sinph0 * sinph0;
204	174	Q->B = cosph0 * cosph0;
205	174	Q->B = sqrt(1. + P->es * Q->B * Q->B / P->one_es);
206	174	Q->A = Q->B * P->k0 * com / con;
207	174	D = Q->B * com / (cosph0 * sqrt(con));
208	174	if ((F = D * D - 1.) <= 0.)
209	0	F = 0.;
210	174	else {
211	174	F = sqrt(F);
212	174	if (P->phi0 < 0.)
213	87	F = -F;
214	174	}
215	174	Q->E = F += D;
216	174	Q->E *= pow(pj_tsfn(P->phi0, sinph0, P->e), Q->B);
217	650	} else {
218	650	Q->B = 1. / com;
219	650	Q->A = P->k0;
220	650	Q->E = D = F = 1.;
221	650	}
222	824	if (alp \|\| gam) {
223	437	if (alp) {
224	384	gamma0 = aasin(P->ctx, sin(alpha_c) / D);
225	384	if (!gam)
226	283	gamma = alpha_c;
227	384	} else {
228	53	gamma0 = gamma;
229	53	alpha_c = aasin(P->ctx, D * sin(gamma0));
230	53	if (proj_errno(P) != 0) {
231		// For a sphere, \|gamma\| must be <= 90 - \|lat_0\|
232		// On an ellipsoid, this is very slightly above
233	0	proj_log_error(P,
234	0	("Invalid value for gamma: given lat_0 value, "
235	0	"\|gamma\| should be <= " +
236	0	std::to_string(asin(1. / D) / M_PI * 180) + "°")
237	0	.c_str());
238	0	return pj_default_destructor(
239	0	P, PROJ_ERR_INVALID_OP_ILLEGAL_ARG_VALUE);
240	0	}
241	53	}
242
243	437	if (fabs(fabs(P->phi0) - M_HALFPI) <= TOL) {
244	1	proj_log_error(
245	1	P, _("Invalid value for lat_0: \|lat_0\| should be < 90°"));
246	1	return pj_default_destructor(P,
247	1	PROJ_ERR_INVALID_OP_ILLEGAL_ARG_VALUE);
248	1	}
249
250	436	P->lam0 = lamc - aasin(P->ctx, .5 * (F - 1. / F) * tan(gamma0)) / Q->B;
251	436	} else {
252	387	H = pow(pj_tsfn(phi1, sin(phi1), P->e), Q->B);
253	387	L = pow(pj_tsfn(phi2, sin(phi2), P->e), Q->B);
254	387	F = Q->E / H;
255	387	p = (L - H) / (L + H);
256	387	if (p == 0) {
257		// Not quite, but es is very close to 1...
258	0	proj_log_error(P, _("Invalid value for eccentricity"));
259	0	return pj_default_destructor(P,
260	0	PROJ_ERR_INVALID_OP_ILLEGAL_ARG_VALUE);
261	0	}
262	387	J = Q->E * Q->E;
263	387	J = (J - L * H) / (J + L * H);
264	387	if ((con = lam1 - lam2) < -M_PI)
265	20	lam2 -= M_TWOPI;
266	367	else if (con > M_PI)
267	9	lam2 += M_TWOPI;
268	387	P->lam0 = adjlon(.5 * (lam1 + lam2) -
269	387	atan(J * tan(.5 * Q->B * (lam1 - lam2)) / p) / Q->B);
270	387	const double denom = F - 1. / F;
271	387	if (denom == 0) {
272	0	proj_log_error(P, _("Invalid value for eccentricity"));
273	0	return pj_default_destructor(P,
274	0	PROJ_ERR_INVALID_OP_ILLEGAL_ARG_VALUE);
275	0	}
276	387	gamma0 = atan(2. * sin(Q->B * adjlon(lam1 - P->lam0)) / denom);
277	387	gamma = alpha_c = aasin(P->ctx, D * sin(gamma0));
278	387	}
279	823	Q->singam = sin(gamma0);
280	823	Q->cosgam = cos(gamma0);
281	823	Q->sinrot = sin(gamma);
282	823	Q->cosrot = cos(gamma);
283	823	Q->BrA = 1. / (Q->ArB = Q->A * (Q->rB = 1. / Q->B));
284	823	Q->AB = Q->A * Q->B;
285	823	if (no_off)
286	74	Q->u_0 = 0;
287	749	else {
288	749	Q->u_0 = fabs(Q->ArB * atan(sqrt(D * D - 1.) / cos(alpha_c)));
289	749	if (P->phi0 < 0.)
290	87	Q->u_0 = -Q->u_0;
291	749	}
292	823	F = 0.5 * gamma0;
293	823	Q->v_pole_n = Q->ArB * log(tan(M_FORTPI - F));
294	823	Q->v_pole_s = Q->ArB * log(tan(M_FORTPI + F));
295	823	P->inv = omerc_e_inverse;
296	823	P->fwd = omerc_e_forward;
297
298	823	return P;
299	824	}
300
301		#undef TOL
302		#undef EPS