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/*
** libproj -- library of cartographic projections
**
** Copyright (c) 2003, 2006 Gerald I. Evenden
*/
static const char
LIBPROJ_ID[] = "Id";
/*
** 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.
*/
#define PROJ_PARMS__ \
double theta; \
double m, n; \
double two_r_m, two_r_n, rm, rn, hm, hn; \
double cp0, sp0;
#define PROJ_LIB__
#include <lib_proj.h>
PROJ_HEAD(oea, "Oblated Equal Area") "\n\tMisc Sph\n\tn= m= theta=";
FORWARD(s_forward); /* sphere */
double Az, M, N, cp, sp, cl, shz;
cp = cos(lp.phi);
sp = sin(lp.phi);
cl = cos(lp.lam);
Az = proj_atan2(cp * sin(lp.lam), P->cp0 * sp - P->sp0 * cp * cl) + P->theta;
shz = sin(0.5 * proj_acos(P->sp0 * sp + P->cp0 * cp * cl));
M = proj_asin(shz * sin(Az));
N = proj_asin(shz * cos(Az) * cos(M) / cos(M * P->two_r_m));
xy.y = P->n * sin(N * P->two_r_n);
xy.x = P->m * sin(M * P->two_r_m) * cos(N) / cos(N * P->two_r_n);
return (xy);
}
INVERSE(s_inverse); /* sphere */
double N, M, xp, yp, z, Az, cz, sz, cAz;
N = P->hn * proj_asin(xy.y * P->rn);
M = P->hm * proj_asin(xy.x * P->rm * cos(N * P->two_r_n) / cos(N));
xp = 2. * sin(M);
yp = 2. * sin(N) * cos(M * P->two_r_m) / cos(M);
cAz = cos(Az = proj_atan2(xp, yp) - P->theta);
z = 2. * proj_asin(0.5 * hypot(xp, yp));
sz = sin(z);
cz = cos(z);
lp.phi = proj_asin(P->sp0 * cz + P->cp0 * sz * cAz);
lp.lam = proj_atan2(sz * sin(Az),
P->cp0 * cz - P->sp0 * sz * cAz);
return (lp);
}
FREEUP; if (P) free(P); }
ENTRY0(oea)
if (((P->n = proj_param(P->params, "dn").f) <= 0.) ||
((P->m = proj_param(P->params, "dm").f) <= 0.))
E_ERROR(-39)
else {
P->theta = proj_param(P->params, "rtheta").f;
P->sp0 = sin(P->phi0);
P->cp0 = cos(P->phi0);
P->rn = 1./ P->n;
P->rm = 1./ P->m;
P->two_r_n = 2. * P->rn;
P->two_r_m = 2. * P->rm;
P->hm = 0.5 * P->m;
P->hn = 0.5 * P->n;
P->fwd = s_forward;
P->inv = s_inverse;
P->es = 0.;
}
ENDENTRY(P)
/*
** Log: proj_oea.c
** Revision 3.1 2006/01/11 01:38:18 gie
** Initial
**
*/
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