public static double dot ( NumberVector v1 , NumberVector v2 ) { // Java Hotspot appears to optimize these better than if-then-else: return v1 instanceof SparseNumberVector ? // v2 instanceof SparseNumberVector ? // dotSparse ( ( SparseNumberVector ) v1 , ( SparseNumberVector ) v2 ) : // dotSparseDense ( ( SparseNumberVector ) v1 , v2 ) : // v2 instanceof SparseNumberVector ? // dotSparseDense ( ( SparseNumberVector ) v2 , v1 ) : // dotDense ( v1 , v2 ) ; }
Compute the dot product of the angle between two vectors .