/*
** libproj -- library of cartographic projections
**
** Copyright (c) 2003, 2005, 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 PROJ_PARMS__\
  int  sym;
#include  <lib_proj.h>
PROJ_HEAD(hatano, "Hatano Equal Area") "\n\tPCyl, Sph.\n[tsym=]";
#define NITER  20
#define EPS  1e-7
#define ONETOL 1.000001
#define CN  2.67595
#define CS  2.43763
#define RCN  0.37369906014686373063
#define RCS  0.41023453108141924738
#define FYCN  1.75859
#define FYCS  1.93052
#define RYCN  0.56863737426006061674
#define RYCS  0.51799515156538134803
#define FXC  0.85
#define RXC  1.17647058823529411764
FORWARD(s_forward); /* spheroid */
  double th1, c;
  int i, opt = !P->sym && (lp.phi < 0.);

  c = sin(lp.phi) * (opt ? CS : CN);
  for (i = NITER; i; --i) {
    lp.phi -= th1 = (lp.phi + sin(lp.phi) - c) / (1. + cos(lp.phi));
    if (fabs(th1) < EPS) break;
  }
  xy.x = FXC * lp.lam * cos(lp.phi *= .5);
  xy.y = sin(lp.phi) * (opt ? FYCS : FYCN);
  return (xy);
}
INVERSE(s_inverse); /* spheroid */
  double th;
  int opt = !P->sym && (xy.y < 0.);

  th = xy.y * ( opt ? RYCS : RYCN);
  if (fabs(th) > 1.)
    if (fabs(th) > ONETOL)  I_ERROR
    else      th = th > 0. ? HALFPI : - HALFPI;
  else
    th = asin(th);
  lp.lam = RXC * xy.x / cos(th);
  th += th;
  lp.phi = (th + sin(th)) * (opt ? RCS : RCN);
  if (fabs(lp.phi) > 1.)
    if (fabs(lp.phi) > ONETOL)  I_ERROR
    else      lp.phi = lp.phi > 0. ? HALFPI : - HALFPI;
  else
    lp.phi = asin(lp.phi);
  return (lp);
}
FREEUP; if (P) free(P); }
ENTRY0(hatano)
  P->sym = proj_param(P->params, "tsym").i;
  P->es = 0.;
  P->inv = s_inverse;
  P->fwd = s_forward;
ENDENTRY(P)
/*
** Log: proj_hatano.c
** Revision 3.1  2006/01/11 01:38:18  gie
** Initial
**
*/