public KDTreeXYZ(List <XYZ> _coords)
{
//construct KNN tree,
var tree_nodes = convertFromXYZ(_coords);
int[] tree_tags = Enumerable.Range(0, _coords.Count).ToArray();
this.tree = new alglib.kdtree();
alglib.kdtreebuildtagged(tree_nodes, tree_tags, 3, 0, 2, out tree);
}
private static extern void kdtreebuild(double[,] xy, int nx, int ny, int normtypeout, out alglib.kdtree kdt, alglib.xparams _params);
private static extern int kdtreequeryknn(alglib.kdtree kdt, double[] x, int k, alglib.xparams _params);
