/src/PROJ/src/projections/igh.cpp

Source


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

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

PROJ_HEAD(igh, "Interrupted Goode Homolosine") "\n\tPCyl, Sph";

/*
This projection is a compilation of 12 separate sub-projections.
Sinusoidal projections are found near the equator and Mollweide
projections are found at higher latitudes. The transition between
the two occurs at 40 degrees latitude and is represented by the
constant `igh_phi_boundary`.

Each sub-projection is assigned an integer label
numbered 1 through 12. Most of this code contains logic to assign
the labels based on latitude (phi) and longitude (lam) regions.

Original Reference:
J. Paul Goode (1925) THE HOMOLOSINE PROJECTION: A NEW DEVICE FOR
    PORTRAYING THE EARTH'S SURFACE ENTIRE, Annals of the Association of
    American Geographers, 15:3, 119-125, DOI: 10.1080/00045602509356949
*/

C_NAMESPACE PJ *pj_sinu(PJ *), *pj_moll(PJ *);

/*
Transition from sinusoidal to Mollweide projection
Latitude (phi): 40deg 44' 11.8"
*/

constexpr double igh_phi_boundary = (40 + 44 / 60. + 11.8 / 3600.) * DEG_TO_RAD;

namespace pj_igh_ns {
struct pj_igh_data {
    struct PJconsts *pj[12];
    double dy0;
};

constexpr double d10 = 10 * DEG_TO_RAD;
constexpr double d20 = 20 * DEG_TO_RAD;
constexpr double d30 = 30 * DEG_TO_RAD;
constexpr double d40 = 40 * DEG_TO_RAD;
constexpr double d50 = 50 * DEG_TO_RAD;
constexpr double d60 = 60 * DEG_TO_RAD;
constexpr double d80 = 80 * DEG_TO_RAD;
constexpr double d90 = 90 * DEG_TO_RAD;
constexpr double d100 = 100 * DEG_TO_RAD;
constexpr double d140 = 140 * DEG_TO_RAD;
constexpr double d160 = 160 * DEG_TO_RAD;
constexpr double d180 = 180 * DEG_TO_RAD;

constexpr double EPSLN =
    1.e-10; /* allow a little 'slack' on zone edge positions */

} // namespace pj_igh_ns

static PJ_XY igh_s_forward(PJ_LP lp, PJ *P) { /* Spheroidal, forward */
    using namespace pj_igh_ns;
    PJ_XY xy;
    struct pj_igh_data *Q = static_cast<struct pj_igh_data *>(P->opaque);
    int z;

    if (lp.phi >= igh_phi_boundary) { /* 1|2 */
        z = (lp.lam <= -d40 ? 1 : 2);
    } else if (lp.phi >= 0) { /* 3|4 */
        z = (lp.lam <= -d40 ? 3 : 4);
    } else if (lp.phi >= -igh_phi_boundary) { /* 5|6|7|8 */
        if (lp.lam <= -d100)
            z = 5; /* 5 */
        else if (lp.lam <= -d20)
            z = 6; /* 6 */
        else if (lp.lam <= d80)
            z = 7; /* 7 */
        else
            z = 8; /* 8 */
    } else {       /* 9|10|11|12 */
        if (lp.lam <= -d100)
            z = 9; /* 9 */
        else if (lp.lam <= -d20)
            z = 10; /* 10 */
        else if (lp.lam <= d80)
            z = 11; /* 11 */
        else
            z = 12; /* 12 */
    }

    lp.lam -= Q->pj[z - 1]->lam0;
    xy = Q->pj[z - 1]->fwd(lp, Q->pj[z - 1]);
    xy.x += Q->pj[z - 1]->x0;
    xy.y += Q->pj[z - 1]->y0;

    return xy;
}

static PJ_LP igh_s_inverse(PJ_XY xy, PJ *P) { /* Spheroidal, inverse */
    using namespace pj_igh_ns;
    PJ_LP lp = {0.0, 0.0};
    struct pj_igh_data *Q = static_cast<struct pj_igh_data *>(P->opaque);
    const double y90 =
        Q->dy0 + sqrt(2.0); /* lt=90 corresponds to y=y0+sqrt(2) */

    int z = 0;
    if (xy.y > y90 + EPSLN || xy.y < -y90 + EPSLN) /* 0 */
        z = 0;
    else if (xy.y >= igh_phi_boundary) /* 1|2 */
        z = (xy.x <= -d40 ? 1 : 2);
    else if (xy.y >= 0) /* 3|4 */
        z = (xy.x <= -d40 ? 3 : 4);
    else if (xy.y >= -igh_phi_boundary) { /* 5|6|7|8 */
        if (xy.x <= -d100)
            z = 5; /* 5 */
        else if (xy.x <= -d20)
            z = 6; /* 6 */
        else if (xy.x <= d80)
            z = 7; /* 7 */
        else
            z = 8; /* 8 */
    } else {       /* 9|10|11|12 */
        if (xy.x <= -d100)
            z = 9; /* 9 */
        else if (xy.x <= -d20)
            z = 10; /* 10 */
        else if (xy.x <= d80)
            z = 11; /* 11 */
        else
            z = 12; /* 12 */
    }

    if (z) {
        bool ok = false;

        xy.x -= Q->pj[z - 1]->x0;
        xy.y -= Q->pj[z - 1]->y0;
        lp = Q->pj[z - 1]->inv(xy, Q->pj[z - 1]);
        lp.lam += Q->pj[z - 1]->lam0;

        switch (z) {
        case 1:
            ok = (lp.lam >= -d180 - EPSLN && lp.lam <= -d40 + EPSLN) ||
                 ((lp.lam >= -d40 - EPSLN && lp.lam <= -d10 + EPSLN) &&
                  (lp.phi >= d60 - EPSLN && lp.phi <= d90 + EPSLN));
            break;
        case 2:
            ok = (lp.lam >= -d40 - EPSLN && lp.lam <= d180 + EPSLN) ||
                 ((lp.lam >= -d180 - EPSLN && lp.lam <= -d160 + EPSLN) &&
                  (lp.phi >= d50 - EPSLN && lp.phi <= d90 + EPSLN)) ||
                 ((lp.lam >= -d50 - EPSLN && lp.lam <= -d40 + EPSLN) &&
                  (lp.phi >= d60 - EPSLN && lp.phi <= d90 + EPSLN));
            break;
        case 3:
            ok = (lp.lam >= -d180 - EPSLN && lp.lam <= -d40 + EPSLN);
            break;
        case 4:
            ok = (lp.lam >= -d40 - EPSLN && lp.lam <= d180 + EPSLN);
            break;
        case 5:
            ok = (lp.lam >= -d180 - EPSLN && lp.lam <= -d100 + EPSLN);
            break;
        case 6:
            ok = (lp.lam >= -d100 - EPSLN && lp.lam <= -d20 + EPSLN);
            break;
        case 7:
            ok = (lp.lam >= -d20 - EPSLN && lp.lam <= d80 + EPSLN);
            break;
        case 8:
            ok = (lp.lam >= d80 - EPSLN && lp.lam <= d180 + EPSLN);
            break;
        case 9:
            ok = (lp.lam >= -d180 - EPSLN && lp.lam <= -d100 + EPSLN);
            break;
        case 10:
            ok = (lp.lam >= -d100 - EPSLN && lp.lam <= -d20 + EPSLN);
            break;
        case 11:
            ok = (lp.lam >= -d20 - EPSLN && lp.lam <= d80 + EPSLN);
            break;
        case 12:
            ok = (lp.lam >= d80 - EPSLN && lp.lam <= d180 + EPSLN);
            break;
        }
        z = (!ok ? 0 : z); /* projectable? */
    }

    if (!z)
        lp.lam = HUGE_VAL;
    if (!z)
        lp.phi = HUGE_VAL;

    return lp;
}

static PJ *pj_igh_data_destructor(PJ *P, int errlev) {
    using namespace pj_igh_ns;
    int i;
    if (nullptr == P)
        return nullptr;

    if (nullptr == P->opaque)
        return pj_default_destructor(P, errlev);

    struct pj_igh_data *Q = static_cast<struct pj_igh_data *>(P->opaque);

    for (i = 0; i < 12; ++i) {
        if (Q->pj[i])
            Q->pj[i]->destructor(Q->pj[i], errlev);
    }

    return pj_default_destructor(P, errlev);
}

/*
  Zones:

    -180            -40                       180
      +--------------+-------------------------+    Zones 1,2,9,10,11 & 12:
      |1             |2                        |      Mollweide projection
      |              |                         |
      +--------------+-------------------------+    Zones 3,4,5,6,7 & 8:
      |3             |4                        |      Sinusoidal projection
      |              |                         |
    0 +-------+------+-+-----------+-----------+
      |5      |6       |7          |8          |
      |       |        |           |           |
      +-------+--------+-----------+-----------+
      |9      |10      |11         |12         |
      |       |        |           |           |
      +-------+--------+-----------+-----------+
    -180    -100      -20         80          180
*/

static bool pj_igh_setup_zone(PJ *P, struct pj_igh_ns::pj_igh_data *Q, int n,
                              PJ *(*proj_ptr)(PJ *), double x_0, double y_0,
                              double lon_0) {
    if (!(Q->pj[n - 1] = proj_ptr(nullptr)))
        return false;
    if (!(Q->pj[n - 1] = proj_ptr(Q->pj[n - 1])))
        return false;
    Q->pj[n - 1]->ctx = P->ctx;
    Q->pj[n - 1]->x0 = x_0;
    Q->pj[n - 1]->y0 = y_0;
    Q->pj[n - 1]->lam0 = lon_0;
    return true;
}

PJ *PJ_PROJECTION(igh) {
    using namespace pj_igh_ns;

    PJ_XY xy1, xy3;
    PJ_LP lp = {0, igh_phi_boundary};
    struct pj_igh_data *Q = static_cast<struct pj_igh_data *>(
        calloc(1, sizeof(struct pj_igh_data)));
    if (nullptr == Q)
        return pj_default_destructor(P, PROJ_ERR_OTHER /*ENOMEM*/);
    P->opaque = Q;

    /* sinusoidal zones */
    if (!pj_igh_setup_zone(P, Q, 3, pj_sinu, -d100, 0, -d100) ||
        !pj_igh_setup_zone(P, Q, 4, pj_sinu, d30, 0, d30) ||
        !pj_igh_setup_zone(P, Q, 5, pj_sinu, -d160, 0, -d160) ||
        !pj_igh_setup_zone(P, Q, 6, pj_sinu, -d60, 0, -d60) ||
        !pj_igh_setup_zone(P, Q, 7, pj_sinu, d20, 0, d20) ||
        !pj_igh_setup_zone(P, Q, 8, pj_sinu, d140, 0, d140)) {
        return pj_igh_data_destructor(P, PROJ_ERR_OTHER /*ENOMEM*/);
    }

    /* mollweide zones */
    if (!pj_igh_setup_zone(P, Q, 1, pj_moll, -d100, 0, -d100)) {
        return pj_igh_data_destructor(P, PROJ_ERR_OTHER /*ENOMEM*/);
    }

    /* y0 ? */
    xy1 = Q->pj[0]->fwd(lp, Q->pj[0]); /* zone 1 */
    xy3 = Q->pj[2]->fwd(lp, Q->pj[2]); /* zone 3 */
    /* y0 + xy1.y = xy3.y for lt = 40d44'11.8" */
    Q->dy0 = xy3.y - xy1.y;

    Q->pj[0]->y0 = Q->dy0;

    /* mollweide zones (cont'd) */
    if (!pj_igh_setup_zone(P, Q, 2, pj_moll, d30, Q->dy0, d30) ||
        !pj_igh_setup_zone(P, Q, 9, pj_moll, -d160, -Q->dy0, -d160) ||
        !pj_igh_setup_zone(P, Q, 10, pj_moll, -d60, -Q->dy0, -d60) ||
        !pj_igh_setup_zone(P, Q, 11, pj_moll, d20, -Q->dy0, d20) ||
        !pj_igh_setup_zone(P, Q, 12, pj_moll, d140, -Q->dy0, d140)) {
        return pj_igh_data_destructor(P, PROJ_ERR_OTHER /*ENOMEM*/);
    }

    P->inv = igh_s_inverse;
    P->fwd = igh_s_forward;
    P->destructor = pj_igh_data_destructor;
    P->es = 0.;

    return P;
}

Coverage Report

Created: 2026-04-09 06:50

Line	Count	Source
1
2
3		#include <errno.h>
4		#include <math.h>
5
6		#include "proj.h"
7		#include "proj_internal.h"
8
9		PROJ_HEAD(igh, "Interrupted Goode Homolosine") "\n\tPCyl, Sph";
10
11		/*
12		This projection is a compilation of 12 separate sub-projections.
13		Sinusoidal projections are found near the equator and Mollweide
14		projections are found at higher latitudes. The transition between
15		the two occurs at 40 degrees latitude and is represented by the
16		constant `igh_phi_boundary`.
17
18		Each sub-projection is assigned an integer label
19		numbered 1 through 12. Most of this code contains logic to assign
20		the labels based on latitude (phi) and longitude (lam) regions.
21
22		Original Reference:
23		J. Paul Goode (1925) THE HOMOLOSINE PROJECTION: A NEW DEVICE FOR
24		PORTRAYING THE EARTH'S SURFACE ENTIRE, Annals of the Association of
25		American Geographers, 15:3, 119-125, DOI: 10.1080/00045602509356949
26		*/
27
28		C_NAMESPACE PJ pj_sinu(PJ ), pj_moll(PJ );
29
30		/*
31		Transition from sinusoidal to Mollweide projection
32		Latitude (phi): 40deg 44' 11.8"
33		*/
34
35		constexpr double igh_phi_boundary = (40 + 44 / 60. + 11.8 / 3600.) * DEG_TO_RAD;
36
37		namespace pj_igh_ns {
38		struct pj_igh_data {
39		struct PJconsts *pj[12];
40		double dy0;
41		};
42
43		constexpr double d10 = 10 * DEG_TO_RAD;
44		constexpr double d20 = 20 * DEG_TO_RAD;
45		constexpr double d30 = 30 * DEG_TO_RAD;
46		constexpr double d40 = 40 * DEG_TO_RAD;
47		constexpr double d50 = 50 * DEG_TO_RAD;
48		constexpr double d60 = 60 * DEG_TO_RAD;
49		constexpr double d80 = 80 * DEG_TO_RAD;
50		constexpr double d90 = 90 * DEG_TO_RAD;
51		constexpr double d100 = 100 * DEG_TO_RAD;
52		constexpr double d140 = 140 * DEG_TO_RAD;
53		constexpr double d160 = 160 * DEG_TO_RAD;
54		constexpr double d180 = 180 * DEG_TO_RAD;
55
56		constexpr double EPSLN =
57		1.e-10; /* allow a little 'slack' on zone edge positions */
58
59		} // namespace pj_igh_ns
60
61	4.11k	static PJ_XY igh_s_forward(PJ_LP lp, PJ P) { / Spheroidal, forward */
62	4.11k	using namespace pj_igh_ns;
63	4.11k	PJ_XY xy;
64	4.11k	struct pj_igh_data Q = static_cast<struct pj_igh_data >(P->opaque);
65	4.11k	int z;
66
67	4.11k	if (lp.phi >= igh_phi_boundary) { /* 1\|2 */
68	1.91k	z = (lp.lam <= -d40 ? 1 : 2);
69	2.19k	} else if (lp.phi >= 0) { /* 3\|4 */
70	2.19k	z = (lp.lam <= -d40 ? 3 : 4);
71	2.19k	} else if (lp.phi >= -igh_phi_boundary) { /* 5\|6\|7\|8 */
72	0	if (lp.lam <= -d100)
73	0	z = 5; /* 5 */
74	0	else if (lp.lam <= -d20)
75	0	z = 6; /* 6 */
76	0	else if (lp.lam <= d80)
77	0	z = 7; /* 7 */
78	0	else
79	0	z = 8; /* 8 */
80	0	} else { /* 9\|10\|11\|12 */
81	0	if (lp.lam <= -d100)
82	0	z = 9; /* 9 */
83	0	else if (lp.lam <= -d20)
84	0	z = 10; /* 10 */
85	0	else if (lp.lam <= d80)
86	0	z = 11; /* 11 */
87	0	else
88	0	z = 12; /* 12 */
89	0	}
90
91	4.11k	lp.lam -= Q->pj[z - 1]->lam0;
92	4.11k	xy = Q->pj[z - 1]->fwd(lp, Q->pj[z - 1]);
93	4.11k	xy.x += Q->pj[z - 1]->x0;
94	4.11k	xy.y += Q->pj[z - 1]->y0;
95
96	4.11k	return xy;
97	4.11k	}
98
99	0	static PJ_LP igh_s_inverse(PJ_XY xy, PJ P) { / Spheroidal, inverse */
100	0	using namespace pj_igh_ns;
101	0	PJ_LP lp = {0.0, 0.0};
102	0	struct pj_igh_data Q = static_cast<struct pj_igh_data >(P->opaque);
103	0	const double y90 =
104	0	Q->dy0 + sqrt(2.0); /* lt=90 corresponds to y=y0+sqrt(2) */
105
106	0	int z = 0;
107	0	if (xy.y > y90 + EPSLN \|\| xy.y < -y90 + EPSLN) /* 0 */
108	0	z = 0;
109	0	else if (xy.y >= igh_phi_boundary) /* 1\|2 */
110	0	z = (xy.x <= -d40 ? 1 : 2);
111	0	else if (xy.y >= 0) /* 3\|4 */
112	0	z = (xy.x <= -d40 ? 3 : 4);
113	0	else if (xy.y >= -igh_phi_boundary) { /* 5\|6\|7\|8 */
114	0	if (xy.x <= -d100)
115	0	z = 5; /* 5 */
116	0	else if (xy.x <= -d20)
117	0	z = 6; /* 6 */
118	0	else if (xy.x <= d80)
119	0	z = 7; /* 7 */
120	0	else
121	0	z = 8; /* 8 */
122	0	} else { /* 9\|10\|11\|12 */
123	0	if (xy.x <= -d100)
124	0	z = 9; /* 9 */
125	0	else if (xy.x <= -d20)
126	0	z = 10; /* 10 */
127	0	else if (xy.x <= d80)
128	0	z = 11; /* 11 */
129	0	else
130	0	z = 12; /* 12 */
131	0	}
132
133	0	if (z) {
134	0	bool ok = false;
135
136	0	xy.x -= Q->pj[z - 1]->x0;
137	0	xy.y -= Q->pj[z - 1]->y0;
138	0	lp = Q->pj[z - 1]->inv(xy, Q->pj[z - 1]);
139	0	lp.lam += Q->pj[z - 1]->lam0;
140
141	0	switch (z) {
142	0	case 1:
143	0	ok = (lp.lam >= -d180 - EPSLN && lp.lam <= -d40 + EPSLN) \|\|
144	0	((lp.lam >= -d40 - EPSLN && lp.lam <= -d10 + EPSLN) &&
145	0	(lp.phi >= d60 - EPSLN && lp.phi <= d90 + EPSLN));
146	0	break;
147	0	case 2:
148	0	ok = (lp.lam >= -d40 - EPSLN && lp.lam <= d180 + EPSLN) \|\|
149	0	((lp.lam >= -d180 - EPSLN && lp.lam <= -d160 + EPSLN) &&
150	0	(lp.phi >= d50 - EPSLN && lp.phi <= d90 + EPSLN)) \|\|
151	0	((lp.lam >= -d50 - EPSLN && lp.lam <= -d40 + EPSLN) &&
152	0	(lp.phi >= d60 - EPSLN && lp.phi <= d90 + EPSLN));
153	0	break;
154	0	case 3:
155	0	ok = (lp.lam >= -d180 - EPSLN && lp.lam <= -d40 + EPSLN);
156	0	break;
157	0	case 4:
158	0	ok = (lp.lam >= -d40 - EPSLN && lp.lam <= d180 + EPSLN);
159	0	break;
160	0	case 5:
161	0	ok = (lp.lam >= -d180 - EPSLN && lp.lam <= -d100 + EPSLN);
162	0	break;
163	0	case 6:
164	0	ok = (lp.lam >= -d100 - EPSLN && lp.lam <= -d20 + EPSLN);
165	0	break;
166	0	case 7:
167	0	ok = (lp.lam >= -d20 - EPSLN && lp.lam <= d80 + EPSLN);
168	0	break;
169	0	case 8:
170	0	ok = (lp.lam >= d80 - EPSLN && lp.lam <= d180 + EPSLN);
171	0	break;
172	0	case 9:
173	0	ok = (lp.lam >= -d180 - EPSLN && lp.lam <= -d100 + EPSLN);
174	0	break;
175	0	case 10:
176	0	ok = (lp.lam >= -d100 - EPSLN && lp.lam <= -d20 + EPSLN);
177	0	break;
178	0	case 11:
179	0	ok = (lp.lam >= -d20 - EPSLN && lp.lam <= d80 + EPSLN);
180	0	break;
181	0	case 12:
182	0	ok = (lp.lam >= d80 - EPSLN && lp.lam <= d180 + EPSLN);
183	0	break;
184	0	}
185	0	z = (!ok ? 0 : z); /* projectable? */
186	0	}
187
188	0	if (!z)
189	0	lp.lam = HUGE_VAL;
190	0	if (!z)
191	0	lp.phi = HUGE_VAL;
192
193	0	return lp;
194	0	}
195
196	108	static PJ pj_igh_data_destructor(PJ P, int errlev) {
197	108	using namespace pj_igh_ns;
198	108	int i;
199	108	if (nullptr == P)
200	0	return nullptr;
201
202	108	if (nullptr == P->opaque)
203	0	return pj_default_destructor(P, errlev);
204
205	108	struct pj_igh_data Q = static_cast<struct pj_igh_data >(P->opaque);
206
207	1.40k	for (i = 0; i < 12; ++i) {
208	1.29k	if (Q->pj[i])
209	1.29k	Q->pj[i]->destructor(Q->pj[i], errlev);
210	1.29k	}
211
212	108	return pj_default_destructor(P, errlev);
213	108	}
214
215		/*
216		Zones:
217
218		-180 -40 180
219		+--------------+-------------------------+ Zones 1,2,9,10,11 & 12:
220		\|1 \|2 \| Mollweide projection
221		\| \| \|
222		+--------------+-------------------------+ Zones 3,4,5,6,7 & 8:
223		\|3 \|4 \| Sinusoidal projection
224		\| \| \|
225		0 +-------+------+-+-----------+-----------+
226		\|5 \|6 \|7 \|8 \|
227		\| \| \| \| \|
228		+-------+--------+-----------+-----------+
229		\|9 \|10 \|11 \|12 \|
230		\| \| \| \| \|
231		+-------+--------+-----------+-----------+
232		-180 -100 -20 80 180
233		*/
234
235		static bool pj_igh_setup_zone(PJ P, struct pj_igh_ns::pj_igh_data Q, int n,
236		PJ (proj_ptr)(PJ *), double x_0, double y_0,
237	1.29k	double lon_0) {
238	1.29k	if (!(Q->pj[n - 1] = proj_ptr(nullptr)))
239	0	return false;
240	1.29k	if (!(Q->pj[n - 1] = proj_ptr(Q->pj[n - 1])))
241	0	return false;
242	1.29k	Q->pj[n - 1]->ctx = P->ctx;
243	1.29k	Q->pj[n - 1]->x0 = x_0;
244	1.29k	Q->pj[n - 1]->y0 = y_0;
245	1.29k	Q->pj[n - 1]->lam0 = lon_0;
246	1.29k	return true;
247	1.29k	}
248
249	108	PJ *PJ_PROJECTION(igh) {
250	108	using namespace pj_igh_ns;
251
252	108	PJ_XY xy1, xy3;
253	108	PJ_LP lp = {0, igh_phi_boundary};
254	108	struct pj_igh_data Q = static_cast<struct pj_igh_data >(
255	108	calloc(1, sizeof(struct pj_igh_data)));
256	108	if (nullptr == Q)
257	0	return pj_default_destructor(P, PROJ_ERR_OTHER /ENOMEM/);
258	108	P->opaque = Q;
259
260		/* sinusoidal zones */
261	108	if (!pj_igh_setup_zone(P, Q, 3, pj_sinu, -d100, 0, -d100) \|\|
262	108	!pj_igh_setup_zone(P, Q, 4, pj_sinu, d30, 0, d30) \|\|
263	108	!pj_igh_setup_zone(P, Q, 5, pj_sinu, -d160, 0, -d160) \|\|
264	108	!pj_igh_setup_zone(P, Q, 6, pj_sinu, -d60, 0, -d60) \|\|
265	108	!pj_igh_setup_zone(P, Q, 7, pj_sinu, d20, 0, d20) \|\|
266	108	!pj_igh_setup_zone(P, Q, 8, pj_sinu, d140, 0, d140)) {
267	0	return pj_igh_data_destructor(P, PROJ_ERR_OTHER /ENOMEM/);
268	0	}
269
270		/* mollweide zones */
271	108	if (!pj_igh_setup_zone(P, Q, 1, pj_moll, -d100, 0, -d100)) {
272	0	return pj_igh_data_destructor(P, PROJ_ERR_OTHER /ENOMEM/);
273	0	}
274
275		/* y0 ? */
276	108	xy1 = Q->pj[0]->fwd(lp, Q->pj[0]); /* zone 1 */
277	108	xy3 = Q->pj[2]->fwd(lp, Q->pj[2]); /* zone 3 */
278		/* y0 + xy1.y = xy3.y for lt = 40d44'11.8" */
279	108	Q->dy0 = xy3.y - xy1.y;
280
281	108	Q->pj[0]->y0 = Q->dy0;
282
283		/* mollweide zones (cont'd) */
284	108	if (!pj_igh_setup_zone(P, Q, 2, pj_moll, d30, Q->dy0, d30) \|\|
285	108	!pj_igh_setup_zone(P, Q, 9, pj_moll, -d160, -Q->dy0, -d160) \|\|
286	108	!pj_igh_setup_zone(P, Q, 10, pj_moll, -d60, -Q->dy0, -d60) \|\|
287	108	!pj_igh_setup_zone(P, Q, 11, pj_moll, d20, -Q->dy0, d20) \|\|
288	108	!pj_igh_setup_zone(P, Q, 12, pj_moll, d140, -Q->dy0, d140)) {
289	0	return pj_igh_data_destructor(P, PROJ_ERR_OTHER /ENOMEM/);
290	0	}
291
292	108	P->inv = igh_s_inverse;
293	108	P->fwd = igh_s_forward;
294	108	P->destructor = pj_igh_data_destructor;
295	108	P->es = 0.;
296
297	108	return P;
298	108	}