private static int GetNearestCluster(double[] point, double[][] centroids, out double error)
        {
            var dataLength = point.Length;

            var centroidIndex = 0;
            var distMin = double.MaxValue;

            for (int c = 0; c < centroids.Length; c++)
            {
                var dist = 0d;
                for (int e = 0; e < dataLength; e++)
                {
                    var temp = point[e] - centroids[c][e];
                    dist += temp * temp;
                }

                if (distMin >= dist)
                {
                    distMin = dist;
                    centroidIndex = c;
                }
            }

            //Błąd jest to kwadrat dystansu od punktu do najbliższego centroidu.
            error = distMin;

            return centroidIndex;
        }