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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; \
void *en;
#define PROJ_LIB__
# include <lib_proj.h>
PROJ_HEAD(cass, "Cassini") "\n\tCyl, Sph&Ell";
# define EPS10 1e-10
# define C1 .16666666666666666666
# define C2 .00833333333333333333
# define C3 .04166666666666666666
# define C4 .33333333333333333333
# define C5 .06666666666666666666
FORWARD(e_forward); /* ellipsoid */
double n, t, tn, a1, c, a2;
xy.y = proj_mdist(lp.phi, n = sin(lp.phi), c = cos(lp.phi), P->en);
n = 1./sqrt(1. - P->es * n * n);
tn = tan(lp.phi); t = tn * tn;
a1 = lp.lam * c;
c *= P->es * c / (1 - P->es);
a2 = a1 * a1;
xy.x = n * a1 * (1. - a2 * t * (C1 - (8. - t + 8. * c) * a2 * C2));
xy.y -= P->m0 - n * tn * a2 * (.5 + (5. - t + 6. * c) * a2 * C3);
return (xy);
}
FORWARD(s_forward); /* spheroid */
xy.x = asin(cos(lp.phi) * sin(lp.lam));
xy.y = atan2(tan(lp.phi) , cos(lp.lam)) - P->phi0;
return (xy);
}
INVERSE(e_inverse); /* ellipsoid */
double phip, n, t, tn, r, dd, d2;
phip = proj_inv_mdist(P->m0 + xy.y, P->en);
if (fabs(fabs(phip) - HALFPI) < TOL) {
lp.phi = phip;
lp.lam = 0;
} else {
tn = tan(phip); t = tn * tn;
n = sin(phip);
r = 1. / (1. - P->es * n * n);
n = sqrt(r);
r *= (1. - P->es) * n;
dd = xy.x / n;
d2 = dd * dd;
lp.phi = phip - (n * tn / r) * d2 * (.5 - (1. + 3. * t) * d2 * C3);
lp.lam = dd * (1. + t * d2 * (-C4 + (1. + 3. * t) * d2 * C5))
/ cos(phip);
}
return (lp);
}
INVERSE(s_inverse); /* spheroid */
double dd = xy.y + P->phi0;
lp.phi = asin(sin(dd) * cos(xy.x));
lp.lam = atan2(tan(xy.x), cos(dd));
return (lp);
}
FREEUP;
if (P) {
if (P->en)
free(P->en);
free(P);
}
}
ENTRY1(cass, en)
if (P->es) {
if (!((P->en = proj_mdist_ini(P->es)))) E_ERROR_0;
P->m0 = proj_mdist(P->phi0, sin(P->phi0), cos(P->phi0), P->en);
P->inv = e_inverse;
P->fwd = e_forward;
} else {
P->inv = s_inverse;
P->fwd = s_forward;
}
ENDENTRY(P)
/*
** Log: proj_cass.c
** Revision 3.1 2006/01/11 01:38:18 gie
** Initial
**
*/
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