Skiddaw Slate (as opposed to Honister slate which has a green hue) and is used for building, in the Lake District. The traditional buildings of Keswick and other settlements are almost entirely of Skiddaw slate. The slate is also used for making souvenirs, monuments, ornaments etc. Smaller fragments are used for gravels or for ornamental pathways. Skiddaw Slate Skiddaw slate is an early Ordovician metamorphosed sedimentary rock, as first identified on the slopes of Skiddaw in the English Lake District. The base of this series is unknown. The thickness could, therefore, amount to several thousand feet of sediment. These sediments were formed
K-means++ the "k"-means++ initialization, the algorithm is guaranteed to find a solution that is O(log "k") competitive to the optimal "k"-means solution. To illustrate the potential of the "k"-means algorithm to perform arbitrarily poorly with respect to the objective function of minimizing the sum of squared distances of cluster points to the centroid of their assigned clusters, consider the example of four points in R that form an axis-aligned rectangle whose width is greater than its height. If "k" = 2 and the two initial cluster centers lie at the midpoints of the top and bottom line segments of the rectangle