question: private static void initializeNNCache ( double [ ] scratch , double [ ] bestd , int [ ] besti ) { final int size = bestd . length ; Arrays . fill ( bestd , Double . POSITIVE_INFINITY ) ; Arrays . fill ( besti , - 1 ) ; for ( int x = 0 , p = 0 ; x < size ; x ++ ) { assert ( p == AGNES . triangleSize ( x ) ) ; double bestdx = Double . POSITIVE_INFINITY ; int bestix = - 1 ; for ( int y = 0 ; y < x ; y ++ , p ++ ) { final double v = scratch [ p ] ; if ( v < bestd [ y ] ) { bestd [ y ] = v ; besti [ y ] = x ; } if ( v < bestdx ) { bestdx = v ; bestix = y ; } } bestd [ x ] = bestdx ; besti [ x ] = bestix ; } }
target:  Initialize the NN cache.