src/projections/wag7.cpp


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#define PJ_LIB__

#include <math.h>

#include "proj.h"
#include "proj_internal.h"

PROJ_HEAD(wag7, "Wagner VII") "\n\tMisc Sph, no inv";


static PJ_XY wag7_s_forward (PJ_LP lp, PJ *P) {           /* Spheroidal, forward */
    PJ_XY xy = {0.0, 0.0};

    (void) P; /* Shut up compiler warnnings about unused P */

    xy.y = 0.90630778703664996 * sin(lp.phi);
    const double theta = asin (xy.y);
    const double ct = cos (theta);
    lp.lam /= 3.;
    xy.x  = 2.66723 * ct * sin (lp.lam);
    const double D = 1/(sqrt (0.5 * (1 + ct * cos (lp.lam))));
    xy.y *= 1.24104 * D;
    xy.x *= D;
    return (xy);
}


PJ *PROJECTION(wag7) {
    P->fwd = wag7_s_forward;
    P->inv = nullptr;
    P->es = 0.;
    return P;
}