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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 qp; \
double *apa;
#define PROJ_LIB__
# include <lib_proj.h>
PROJ_HEAD(cea, "Equal Area Cylindrical") "\n\tCyl, Sph&Ell\n\tlat_ts=(0)";
# define EPS 1e-10
FORWARD(e_forward); /* ellipsoid */
xy.x = P->k0 * lp.lam;
xy.y = .5 * proj_qsfn(lp.phi, P->apa) / P->k0;
return (xy);
}
FORWARD(s_forward); /* spheroid */
xy.x = P->k0 * lp.lam;
xy.y = sin(lp.phi) / P->k0;
return (xy);
}
INVERSE(e_inverse); /* ellipsoid */
lp.phi = proj_auth_inv(asin( 2. * xy.y * P->k0 / P->qp), P->apa);
lp.lam = xy.x / P->k0;
return (lp);
}
INVERSE(s_inverse); /* spheroid */
double t;
if ((t = fabs(xy.y *= P->k0)) - EPS <= 1.) {
if (t >= 1.)
lp.phi = xy.y < 0. ? -HALFPI : HALFPI;
else
lp.phi = asin(xy.y);
lp.lam = xy.x / P->k0;
} else I_ERROR;
return (lp);
}
FREEUP;
if (P) {
if (P->apa)
free(P->apa);
free(P);
}
}
ENTRY1(cea, apa)
double t;
t = proj_param(P->params, "tlat_ts").i ?
proj_param(P->params, "rlat_ts").f : P->phi0;
if ((P->k0 = cos(t)) < 0.) E_ERROR(-24)
if (P->es) {
t = sin(t);
P->k0 /= sqrt(1. - P->es * t * t);
if (!(P->apa = proj_auth_ini(P->es, &t))) E_ERROR_0;
P->qp = proj_qsfn(HALFPI, P->apa);
P->inv = e_inverse;
P->fwd = e_forward;
} else {
P->inv = s_inverse;
P->fwd = s_forward;
}
ENDENTRY(P)
/*
** Log: proj_cea.c
** Revision 3.1 2006/01/11 01:38:18 gie
** Initial
**
*/
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