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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 EPS10 1.e-10
# define TOL7 1.e-7
#define PROJ_PARMS__ \
double ec; \
double n; \
double c; \
double dd; \
double n2; \
double qp; \
double rho0; \
double rho; \
double phi1; \
double phi2; \
void *en; \
void *apa; \
int ellips;
#define PROJ_LIB__
# include <lib_proj.h>
PROJ_HEAD(aea, "Albers Equal Area")
"\n\tConic Sph&Ell\n\tlat_1= lat_2=";
PROJ_HEAD(leac, "Lambert Equal Area Conic")
"\n\tConic, Sph&Ell\n\tlat_1= south";
/* determine latitude angle phi-1 */
# define N_ITER 15
# define EPSILON 1.0e-7
# define TOL 1.0e-10
FORWARD(e_forward); /* ellipsoid & spheroid */
if ((P->rho = P->c - (P->ellips ? P->n * proj_qsfn(lp.phi, P->apa) :
P->n2 * sin(lp.phi))) < 0.) F_ERROR
P->rho = P->dd * sqrt(P->rho);
xy.x = P->rho * sin( lp.lam *= P->n );
xy.y = P->rho0 - P->rho * cos(lp.lam);
return (xy);
}
INVERSE(e_inverse) /* ellipsoid & spheroid */;
if ((P->rho = hypot(xy.x, xy.y = P->rho0 - xy.y))) {
if (P->n < 0.) {
P->rho = -P->rho;
xy.x = -xy.x;
xy.y = -xy.y;
}
lp.phi = P->rho / P->dd;
if (P->ellips) {
lp.phi = (P->c - lp.phi * lp.phi) / P->n;
lp.phi = proj_auth_inv(asin(lp.phi/P->qp), P->apa);
} else if (fabs(lp.phi = (P->c - lp.phi * lp.phi) / P->n2) <= 1.)
lp.phi = asin(lp.phi);
else
lp.phi = lp.phi < 0. ? -HALFPI : HALFPI;
lp.lam = atan2(xy.x, xy.y) / P->n;
} else {
lp.lam = 0.;
lp.phi = P->n > 0. ? HALFPI : - HALFPI;
}
return (lp);
}
FREEUP;
if (P) {
if (P->en) free(P->en);
if (P->apa) free(P->apa);
free(P);
}
}
static PROJ *
setup(PROJ *P) {
double cosphi, sinphi, t;
int secant;
if (fabs(P->phi1 + P->phi2) < EPS10) E_ERROR(-21);
P->n = sinphi = sin(P->phi1);
cosphi = cos(P->phi1);
secant = fabs(P->phi1 - P->phi2) >= EPS10;
if ((P->ellips = P->es > 0.)) {
double ml1, m1;
if (!((P->en = proj_mdist_ini(P->es)))) E_ERROR_0;
if (!((P->apa = proj_auth_ini(P->es, &t)))) E_ERROR_0;
m1 = proj_msfn(sinphi, cosphi, P->es);
ml1 = proj_qsfn(P->phi1, P->apa);
if (secant) { /* secant cone */
double ml2, m2;
sinphi = sin(P->phi2);
cosphi = cos(P->phi2);
m2 = proj_msfn(sinphi, cosphi, P->es);
ml2 = proj_qsfn(P->phi2, P->apa);
P->n = (m1 * m1 - m2 * m2) / (ml2 - ml1);
}
P->ec = 1. - .5 * P->one_es * log((1. - P->e) /
(1. + P->e)) / P->e;
P->c = m1 * m1 + P->n * ml1;
P->dd = 1. / P->n;
P->rho0 = P->dd * sqrt(P->c - P->n * proj_qsfn(P->phi0, P->apa));
P->qp = proj_qsfn(HALFPI, P->apa);
} else {
if (secant) P->n = .5 * (P->n + sin(P->phi2));
P->n2 = P->n + P->n;
P->c = cosphi * cosphi + P->n2 * sinphi;
P->dd = 1. / P->n;
P->rho0 = P->dd * sqrt(P->c - P->n2 * sin(P->phi0));
}
P->inv = e_inverse; P->fwd = e_forward;
return P;
}
ENTRY2(aea, en, apa)
P->phi1 = proj_param(P->params, "rlat_1").f;
P->phi2 = proj_param(P->params, "rlat_2").f;
ENDENTRY(setup(P))
ENTRY2(leac, en, apa)
P->phi2 = proj_param(P->params, "rlat_1").f;
P->phi1 = proj_param(P->params, "bsouth").i ? - HALFPI: HALFPI;
ENDENTRY(setup(P))
/*
** Log: proj_aea.c
** Revision 3.1 2006/01/11 01:38:18 gie
** Initial
**
*/
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