/*
** 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 n, n1;
#define PROJ_LIB__
#include  <lib_proj.h>
PROJ_HEAD(fouc_s, "Foucaut Sinusoidal") "\n\tPCyl., Sph.";
#define MAX_ITER    10
#define LOOP_TOL    1e-7
FORWARD(s_forward); /* spheroid */
  double t;

  t = cos(lp.phi);
  xy.x = lp.lam * t / (P->n + P->n1 * t);
  xy.y = P->n * lp.phi + P->n1 * sin(lp.phi);
  return (xy);
}
INVERSE(s_inverse); /* spheroid */
  double V;
  int i;

  if (P->n) {
    lp.phi = xy.y;
    for (i = MAX_ITER; i ; --i) {
      lp.phi -= V = (P->n * lp.phi + P->n1 * sin(lp.phi) - xy.y ) /
        (P->n + P->n1 * cos(lp.phi));
      if (fabs(V) < LOOP_TOL)
        break;
    }
    if (!i)
      lp.phi = xy.y < 0. ? -HALFPI : HALFPI;
  } else
    lp.phi = proj_asin(xy.y);
  V = cos(lp.phi);
  lp.lam = xy.x * (P->n + P->n1 * V) / V;
  return (lp);
}
FREEUP; if (P) free(P); }
ENTRY0(fouc_s)
  P->n = proj_param(P->params, "dn").f;
  if (P->n < 0. || P->n > 1.)
    E_ERROR(-99)
  P->n1 = 1. - P->n;
  P->es = 0;
  P->inv = s_inverse;
  P->fwd = s_forward;
ENDENTRY(P)
/*
** Log: proj_fouc_s.c
** Revision 3.1  2006/01/11 01:38:18  gie
** Initial
**
*/