/Proj4/PJ_lcc.c

  1#ifndef lint
  2static const char SCCSID[]="@(#)PJ_lcc.c	4.2	94/03/18	GIE	REL";
  3#endif
  4#define PROJ_PARMS__ \
  5	double	phi1; \
  6	double	phi2; \
  7	double	n; \
  8	double	rho; \
  9	double	rho0; \
 10	double	c; \
 11	int		ellips;
 12#define PJ_LIB__
 13#include	"projects.h"
 14PROJ_HEAD(lcc, "Lambert Conformal Conic")
 15	"\n\tConic, Sph&Ell\n\tlat_1= and lat_2= or lat_0";
 16# define EPS10	1.e-10	
 17FORWARD(e_forward); /* ellipsoid & spheroid */
 18	if (fabs(fabs(lp.phi) - HALFPI) < EPS10) {
 19		if ((lp.phi * P->n) <= 0.) F_ERROR;
 20		P->rho = 0.;
 21		}
 22	else
 23		P->rho = P->c * (P->ellips ? pow(pj_tsfn(lp.phi, sin(lp.phi),
 24			P->e), P->n) : pow(tan(FORTPI + .5 * lp.phi), -P->n));
 25	xy.x = P->k0 * (P->rho * sin( lp.lam *= P->n ) );
 26	xy.y = P->k0 * (P->rho0 - P->rho * cos(lp.lam) );
 27	return (xy);
 28}
 29INVERSE(e_inverse); /* ellipsoid & spheroid */
 30	xy.x /= P->k0;
 31	xy.y /= P->k0;
 32	if( (P->rho = hypot(xy.x, xy.y = P->rho0 - xy.y)) != 0.0) {
 33		if (P->n < 0.) {
 34			P->rho = -P->rho;
 35			xy.x = -xy.x;
 36			xy.y = -xy.y;
 37		}
 38		if (P->ellips) {
 39			if ((lp.phi = pj_phi2(pow(P->rho / P->c, 1./P->n), P->e))
 40				== HUGE_VAL)
 41				I_ERROR;
 42		} else
 43			lp.phi = 2. * atan(pow(P->c / P->rho, 1./P->n)) - HALFPI;
 44		lp.lam = atan2(xy.x, xy.y) / P->n;
 45	} else {
 46		lp.lam = 0.;
 47		lp.phi = P->n > 0. ? HALFPI : - HALFPI;
 48	}
 49	return (lp);
 50}
 51SPECIAL(fac) {
 52	if (fabs(fabs(lp.phi) - HALFPI) < EPS10) {
 53		if ((lp.phi * P->n) <= 0.) return;
 54		P->rho = 0.;
 55	} else
 56		P->rho = P->c * (P->ellips ? pow(pj_tsfn(lp.phi, sin(lp.phi),
 57			P->e), P->n) : pow(tan(FORTPI + .5 * lp.phi), -P->n));
 58	fac->code |= IS_ANAL_HK + IS_ANAL_CONV;
 59	fac->k = fac->h = P->k0 * P->n * P->rho /
 60		pj_msfn(sin(lp.phi), cos(lp.phi), P->es);
 61	fac->conv = - P->n * lp.lam;
 62}
 63FREEUP; if (P) pj_dalloc(P); }
 64ENTRY0(lcc)
 65	double cosphi, sinphi;
 66	int secant;
 67
 68	P->phi1 = pj_param(P->params, "rlat_1").f;
 69	if (pj_param(P->params, "tlat_2").i)
 70		P->phi2 = pj_param(P->params, "rlat_2").f;
 71	else {
 72		P->phi2 = P->phi1;
 73		if (!pj_param(P->params, "tlat_0").i)
 74			P->phi0 = P->phi1;
 75	}
 76	if (fabs(P->phi1 + P->phi2) < EPS10) E_ERROR(-21);
 77	P->n = sinphi = sin(P->phi1);
 78	cosphi = cos(P->phi1);
 79	secant = fabs(P->phi1 - P->phi2) >= EPS10;
 80	if( (P->ellips = (P->es != 0.)) ) {
 81		double ml1, m1;
 82
 83		P->e = sqrt(P->es);
 84		m1 = pj_msfn(sinphi, cosphi, P->es);
 85		ml1 = pj_tsfn(P->phi1, sinphi, P->e);
 86		if (secant) { /* secant cone */
 87			P->n = log(m1 /
 88			   pj_msfn(sinphi = sin(P->phi2), cos(P->phi2), P->es));
 89			P->n /= log(ml1 / pj_tsfn(P->phi2, sinphi, P->e));
 90		}
 91		P->c = (P->rho0 = m1 * pow(ml1, -P->n) / P->n);
 92		P->rho0 *= (fabs(fabs(P->phi0) - HALFPI) < EPS10) ? 0. :
 93			pow(pj_tsfn(P->phi0, sin(P->phi0), P->e), P->n);
 94	} else {
 95		if (secant)
 96			P->n = log(cosphi / cos(P->phi2)) /
 97			   log(tan(FORTPI + .5 * P->phi2) /
 98			   tan(FORTPI + .5 * P->phi1));
 99		P->c = cosphi * pow(tan(FORTPI + .5 * P->phi1), P->n) / P->n;
100		P->rho0 = (fabs(fabs(P->phi0) - HALFPI) < EPS10) ? 0. :
101			P->c * pow(tan(FORTPI + .5 * P->phi0), -P->n);
102	}
103	P->inv = e_inverse;
104	P->fwd = e_forward;
105	P->spc = fac;
106ENDENTRY(P)