private void validateCoefficients() {
        if (coefsValid)
            return;

        if (n >= 2) {
            double xBar = (double) sumX / n;
            double yBar = (double) sumY / n;

            a1 = (double) ((n * sumXY - sumX * sumY) / (n * sumXX - sumX * sumX));
            a0 = (double) (yBar - a1 * xBar);
        } else {
            a0 = a1 = Double.NaN;
        }

        coefsValid = true;
    }
private void validateCoefficients ( ) { if ( coefsValid ) return ; if ( n >= 2 ) { double xBar = ( double ) sumX / n ; double yBar = ( double ) sumY / n ; a1 = ( double ) ( ( n * sumXY - sumX * sumY ) / ( n * sumXX - sumX * sumX ) ) ; a0 = ( double ) ( yBar - a1 * xBar ) ; } else { a0 = a1 = Double . NaN ; } coefsValid = true ; }
Validate the coefficients.