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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 TOL 1e-10
#define PROJ_PARMS__ \
double M0, MP; \
double qp; \
void *en; \
void *apa;
#define PROJ_LIB__
# include <lib_proj.h>
PROJ_HEAD(tcea, "Transverse Cylindrical Equal-Area")
"\n\tCyl, Sph&Ell\n\tk_0=(1)";
# define EPS 1e-10
FORWARD(e_forward); /* ellipsoid */
double beta, betac, phic, sc, M;
beta = proj_auth_lat(lp.phi, P->apa);
if (fabs(fabs(lp.lam) - HALFPI) > TOL) {
betac = atan2(tan(beta),cos(lp.lam));
phic = proj_auth_inv(betac, P->apa);
sc = sin(phic);
xy.x = cos(beta)*cos(phic)*sin(lp.lam)/
(P->k0*cos(betac)*sqrt(1.-P->es*sc*sc));
} else {
betac = phic = lp.phi >=0. ? HALFPI : -HALFPI;
sc = lp.phi >= 0. ? 1. : -1.;
xy.x = cos(beta)*sin(lp.lam)/ (P->k0*sqrt(1.-P->es));
}
M = proj_mdist(phic, sc, cos(phic), P->en);
xy.y = P->k0 * (M - P->M0);
return (xy);
}
FORWARD(s_forward); /* spheroid */
xy.x = cos(lp.phi)*sin(lp.lam)/P->k0;
xy.y = P->k0 * (atan2(tan(lp.phi), cos(lp.lam)) - P->phi0);
return (xy);
}
INVERSE(e_inverse); /* ellipsoid */
double phic, betac, betap, beta, sc, t;
t = P->M0 + xy.y/P->k0;
phic = proj_inv_mdist(t, P->en);
sc = sin(phic);
betac = proj_auth_lat(phic, P->apa);
betap = -asin(P->k0 * xy.x * cos(betac) * sqrt(1.-P->es*sc*sc)/cos(phic));
beta = asin(cos(betap) * sin(betac));
lp.lam = - atan2(tan(betap),cos(betac));
if (fabs(t) > P->MP)
lp.lam += lp.lam < 0. ? PI : - PI;
lp.phi = proj_auth_inv(beta, P->apa);
return (lp);
}
INVERSE(s_inverse); /* spheroid */
double t, D, r;
t = xy.x * P->k0;
r = sqrt(1. - t * t);
D = xy.y / P->k0 + P->phi0;
lp.phi = asin(r * sin(D));
lp.lam = atan2(t,(r * cos(D)));
return (lp);
}
FREEUP;
if (P) {
if (P->apa)
free(P->apa);
if (P->en)
free(P->en);
free(P);
}
}
ENTRY2(tcea, apa, en)
double t;
if (P->es) {
if (!(P->apa = proj_auth_ini(P->es, &t))) E_ERROR_0;
if (!(P->en = proj_mdist_ini(P->es))) E_ERROR_0;
P->qp = proj_qsfn(HALFPI, P->apa);
P->M0 = proj_mdist(P->phi0, sin(P->phi0), cos(P->phi0), P->en);
P->MP = proj_mdist(HALFPI, 1., 0., P->en);
P->inv = e_inverse;
P->fwd = e_forward;
} else {
P->inv = s_inverse;
P->fwd = s_forward;
}
ENDENTRY(P)
/*
** Log: proj_tcea.c
** Revision 3.1 2006/01/11 01:38:18 gie
** Initial
**
*/
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