Geo-MedianCenter-XS

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XS.xs  view on Meta::CPAN

    data[ dx + 4 ] = cos(data[ dx ]) * sin(data[ dx + 1 ]); /* y          */
    data[ dx + 5 ] = sin(data[ dx ]);                       /* z          */
  }

  return data;
}

int
median_center(HV* opts, double* plat, double* plon) {

  U32 max_iterations = 4;
  double tolerance = 0.0f;
  SV** value;
  double* data = NULL;
  double clat = 0;
  double clon = 0;
  I32 count = 0;

  if (opts == NULL || !( SvTYPE(opts) == SVt_PVHV )) {
    return -1;
  }

XS.xs  view on Meta::CPAN

      data = data_from_av((AV*)rv);
    }
  }

  value = hv_fetch(opts, "tolerance", 9, 0);

  if (value && *value && SvOK(*value)) {
    tolerance = SvNV(*value);
  }

  value = hv_fetch(opts, "max_iterations", 14, 0);

  if (value && *value && SvOK(*value)) {
    max_iterations = SvUV(*value);
  }

  while (data) {

    double sumkx, sumky, sumkz, sumk, avgx, avgy, avgz, nlat, nlon, ndst;
    size_t last = (count + 1) * 6;
    size_t ix;

    sumkx = sumky = sumkz = sumk = 0;

XS.xs  view on Meta::CPAN

    avgx = sumkx / sumk;
    avgy = sumky / sumk;
    avgz = sumkz / sumk;

    /* Should this rather use asin(avgz)? */
    nlat = atan2(avgz, sqrt(avgx * avgx + avgy * avgy));
    nlon = atan2(avgy, avgx);

    ndst = haversine_distance_rad(clat, clon, nlat, nlon);

    if (!(max_iterations-- > 0) || (ndst <= tolerance)) {
      *plat = nlat * (180.0 / PI);
      *plon = nlon * (180.0 / PI);

      Safefree(data);
      
      return 0;
    }

    clat = nlat;
    clon = nlon;

lib/Geo/MedianCenter/XS.pm  view on Meta::CPAN

=head2 FUNCTIONS

=over 2

=item median_center(\%options)

Computes the median center of a list of points. Options are C<points>,
an array of arrays of latitude and longitude in decimal degrees and
optionally a weight; C<tolerance>, a number in meters, if the iterative
algorithm improves its approximation by at most this value, the function
will return; C<max_iterations>, the function will return after this
many attempts to refine the approximation. Returns the latitude and
longitude in decimal degrees.

=item haversine_distance_dec($lat1, $lon1, $lat2, $long2)

Computes the distance between the two points using the Haversine
formula in meters. Latitude and longitude are specified in decimal
degrees.

=item haversine_distance_rad($lat1, $lon1, $lat2, $long2)