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XS.xs  view on Meta::CPAN

    double s, c, omega, rr, aa, bb, pp, qq, d2, qp, eps1, eps2;

    if (s2 == 0.) return 0.;
    if (c2 == 0.) return M_PI * RM / KILOMETER_RHO * 0.001;

    s = sqrt(s2), c = sqrt(c2);
    omega = atan2(s, c);
    rr = s * c;
    aa = s2g * c2f / s2 + s2f * c2g / c2;
    bb = s2g * c2f / s2 - s2f * c2g / c2;
    pp = rr / omega;
    qq = omega / rr;
    d2 = s2 - c2;
    qp = qq + 6. * pp;
    eps1 = 0.5 * F * (-aa - 3. * bb * pp);
    eps2 = 0.25 * F * F * ((-qp * bb + (-3.75 + d2 * (qq + 3.75 * pp)) *
            aa + 4. - d2 * qq) * aa - (7.5 * d2 * bb * pp - qp) * bb);

    double d = 2. * omega * A * (1. + eps1 + eps2);
    return d / KILOMETER_RHO * 0.001;
}

/* TODO: add more guards against unexpected data */
double
_count_units (SV *self, SV *unit) {
    dTHX;

    STRLEN len;
    char *name = SvPV(unit, len);
    HV *hash;

    SV **svp = hv_fetchs((HV *)SvRV(self), "units", 0);
    if (! svp) my_croak("Unknown unit type \"%s\"", name);

    hash = (HV *)SvRV(*svp);
    svp = hv_fetch(hash, name, len, 0);
    if (! svp) my_croak("Unknown unit type \"%s\"", name);

    return SvNV(*svp);
}

MODULE = Geo::Distance::XS    PACKAGE = Geo::Distance::XS

PROTOTYPES: DISABLE

void
distance (self, unit, lon1, lat1, lon2, lat2)
    SV *self
    SV *unit
    NV lon1
    NV lat1
    NV lon2
    NV lat2
PREINIT:
    SV **key;
    int index = 1;
    double (*func)(double, double, double, double);
CODE:
    if (lat2 == lat1 && lon2 == lon1)
        XSRETURN_NV(0.);
    key = hv_fetchs((HV *)SvRV(self), "formula_index", 0);
    if (key) index = SvIV(*key);
    switch (index) {
        case 1: func = &haversine; break;
        case 2: func = &cosines; break;
        case 3: func = &vincenty; break;
        case 4: func = &great_circle; break;
        case 5: func = &polar; break;
        case 6: func = &andoyer_lambert_thomas; break;
    }
    XSRETURN_NV(_count_units(self, unit) * (*func)(lat1, lon1, lat2, lon2));