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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_LIB__
#define N_TOL 1e-6
#define TOL 1e-7
#define PROJ_PARMS__ \
double n, np; \
int mode;
# include <lib_proj.h>
PROJ_HEAD(tob_g1, "Tobler G1") "\n\tPCyl., Sph., [n=] NoInv.";
FORWARD(s_forward); /* spheroid */
double cosphi, sinphi, aphi;
if ((aphi = fabs(lp.phi)) < TOL) {
xy.y = 0.;
xy.x = lp.lam;
} else {
cosphi = cos(aphi);
sinphi = sin(aphi);
if (P->mode) {
xy.y = sqrt(aphi * sinphi);
xy.x = 2.0 * lp.lam * cosphi * xy.y/(sinphi + aphi * cosphi);
} else {
xy.y = pow(aphi, P->n) * pow(fabs(sinphi),P->np);
xy.x = lp.lam * cosphi *
pow(fabs(aphi), P->np) * pow(fabs(sinphi),P->n) /
(P->n * sinphi + P->np * aphi * cosphi);
}
if (lp.phi < 0.)
xy.y = -xy.y;
}
return (xy);
}
FREEUP; if (P) free(P); }
ENTRY0(tob_g1)
P->es = 0.;
if (proj_param(P->params, "tn").i) {
P->n = proj_param(P->params, "dn").f;
if ((P->n < N_TOL) || (P->n > 1.-N_TOL))
E_ERROR(-40)
} else
P->n = 0.5;
P->np = 1.0 - P->n;
P->mode = fabs(P->n - 0.5) < N_TOL;
P->fwd = s_forward;
ENDENTRY(P)
/*
** Log: proj_tob_g1.c
** Revision 3.1 2006/01/11 01:38:18 gie
** Initial
**
*/
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