svn-gvsig-desktop / tags / gvsig_redes-1_0_0-1235 / libraries / libjni-proj4 / src / PJ_eck2.c @ 44116
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#ifndef lint
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static const char SCCSID[]="@(#)PJ_eck2.c 4.1 94/02/15 GIE REL"; |
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#endif
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#define PJ_LIB__
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# include <projects.h> |
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PROJ_HEAD(eck2, "Eckert II") "\n\tPCyl. Sph."; |
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#define FXC 0.46065886596178063902 |
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#define FYC 1.44720250911653531871 |
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#define C13 0.33333333333333333333 |
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#define ONEEPS 1.0000001 |
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FORWARD(s_forward); /* spheroid */
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xy.x = FXC * lp.lam * (xy.y = sqrt(4. - 3. * sin(fabs(lp.phi)))); |
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xy.y = FYC * (2. - xy.y);
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if ( lp.phi < 0.) xy.y = -xy.y; |
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return (xy);
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} |
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INVERSE(s_inverse); /* spheroid */
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lp.lam = xy.x / (FXC * ( lp.phi = 2. - fabs(xy.y) / FYC) );
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lp.phi = (4. - lp.phi * lp.phi) * C13;
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if (fabs(lp.phi) >= 1.) { |
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if (fabs(lp.phi) > ONEEPS) I_ERROR
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else
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lp.phi = lp.phi < 0. ? -HALFPI : HALFPI;
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} else
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lp.phi = asin(lp.phi); |
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if (xy.y < 0) |
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lp.phi = -lp.phi; |
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return (lp);
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} |
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FREEUP; if (P) pj_dalloc(P); }
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ENTRY0(eck2); P->es = 0.; P->inv = s_inverse; P->fwd = s_forward; ENDENTRY(P)
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