question: @ Override protected double evaluate ( int id1 , int id2 , Instance inst1 ) throws Exception { if ( id1 == id2 ) { return 1.0 ; } else { double precalc1 ; if ( id1 == - 1 ) { precalc1 = dotProd ( inst1 , inst1 ) ; } else { precalc1 = m_kernelPrecalc [ id1 ] ; } Instance inst2 = m_data . instance ( id2 ) ; double squaredDifference = - 2.0 * dotProd ( inst1 , inst2 ) + precalc1 + m_kernelPrecalc [ id2 ] ; double intermediate = m_factor * Math . sqrt ( squaredDifference ) ; double result = 1.0 / Math . pow ( 1.0 + intermediate * intermediate , getOmega ( ) ) ; return result ; } }
target:  returns the dot product