Application: gvSIG desktop

/*

** libproj -- library of cartographic projections

**

** Copyright (c) 2003   Gerald I. Evenden

*/

static const char

LIBPROJ_ID[] = "$Id: PJ_sterea.c,v 1.1 2004/10/20 17:04:00 fwarmerdam Exp $";

/*

** 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 phic0; \

        double cosc0, sinc0; \

        double R2; \

        void *en;

#define PJ_LIB__

#include        <projects.h>

PROJ_HEAD(sterea, "Oblique Stereographic Alternative")

        "\n\tAzimuthal, Sph&Ell";

# define DEL_TOL        1.e-14

# define MAX_ITER        10

FORWARD(e_forward); /* ellipsoid */

        double cosc, sinc, cosl, k;

        lp = pj_gauss(lp, P->en);

        sinc = sin(lp.phi);

        cosc = cos(lp.phi);

        cosl = cos(lp.lam);

        k = P->k0 * P->R2 / (1. + P->sinc0 * sinc + P->cosc0 * cosc * cosl);

        xy.x = k * cosc * sin(lp.lam);

        xy.y = k * (P->cosc0 * sinc - P->sinc0 * cosc * cosl);

        return (xy);

}

INVERSE(e_inverse); /* ellipsoid */

        double rho, c, sinc, cosc;

        xy.x /= P->k0;

        xy.y /= P->k0;

        if((rho = hypot(xy.x, xy.y))) {

                c = 2. * atan2(rho, P->R2);

                sinc = sin(c);

                cosc = cos(c);

                lp.phi = asin(cosc * P->sinc0 + xy.y * sinc * P->cosc0 / rho);

                lp.lam = atan2(xy.x * sinc, rho * P->cosc0 * cosc -

                        xy.y * P->sinc0 * sinc);

        } else {

                lp.phi = P->phic0;

                lp.lam = 0.;

        }

        return(pj_inv_gauss(lp, P->en));

}

FREEUP; if (P) { if (P->en) free(P->en); free(P); } }

ENTRY0(sterea)

        double R;

        if (!(P->en = pj_gauss_ini(P->e, P->phi0, &(P->phic0), &R))) E_ERROR_0;

        P->sinc0 = sin(P->phic0);

        P->cosc0 = cos(P->phic0);

        P->R2 = 2. * R;

        P->inv = e_inverse;

        P->fwd = e_forward;

ENDENTRY(P)

/*

** $Log: PJ_sterea.c,v $

** Revision 1.1  2004/10/20 17:04:00  fwarmerdam

** New

**

** Revision 2.3  2004/04/07 17:18:32  gie

** corrected comment stamp

**

** Revision 2.2  2003/08/05 00:15:09  gie

** corrected 0 rho on inverse.

**

** Revision 2.1  2003/03/28 01:46:02  gie

** Initial

**

*/