presto-main/src/main/java/io/prestosql/operator/aggregation/AggregationUtils.java/AggregationUtils/getRegressionSlope
class AggregationUtils:    public static double getRegressionSlope(RegressionState state)
    {
        double dividend = state.getC2();
        double divisor = state.getM2X();

        // divisor deliberately not checked for zero because the result can be Infty or NaN even if it is not zero
        return dividend / divisor;
    }