Blocker Description
Here's some setup code before describing the bug :
Two sum instances are created and assigned Double.POSITIVE_INFINITY as follows:
Sum sum1 = Sum.create(); Sum sum2 = Sum.create(); sum1.add(Double.POSITIVE_INFINITY); sum2.add(Double.POSITIVE_INFINITY);
The `sum` and `comp` fields of both `sum` and `sum2` hold the values `Double.POSITIVE_INFINITY` and `Double.NaN` repectively.
sum2 is added to sum1 as:
sum1.add(sum2);
The `Sum add(Sum other)` returns the value returned by `Sum add(double s, double c)` method.
In the Sum add(double s, double c) method, there's a bug in the return statement :
return add(s).add(c);
When add(c) is executed, c (i.e. sum2.c) which has a value Double.NaN, is causing the sum field of sum1 to be Double.NaN. This is due to :
Sum add(final double t) { // t (= c) final double newSum = sum + t; // Inf + Nan = NaN comp += ExtendedPrecision.twoSumLow(sum, t, newSum); // NaN sum = newSum; // NaN return this; }
Hence, the chaining of add operations should be removed.
The fix would be in the `Sum add(double s, double c)` method as :
Sum add(double s, double c) { add(s); if (!(Double.isNan(comp) && Double.isInfinite(sum))) { add(c); } return this; }
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