A new version is here: http://cr.openjdk.java.net/~bpb/8032027/webrev.05/
I changed the test to verify these values: Stream.Builder<BigInteger> sb = Stream.builder(); int maxExponent = Double.MAX_EXPONENT + 1; for (int i = 1; i <= maxExponent; i++) { BigInteger p2 = BigInteger.ONE.shiftLeft(i); sb.add(p2.subtract(BigInteger.ONE)); sb.add(p2); sb.add(p2.add(BigInteger.ONE)); } sb.add((new BigDecimal(Double.MAX_VALUE)).toBigInteger()); sb.add((new BigDecimal(Double.MAX_VALUE)).toBigInteger().add(BigInteger.ONE)); report("squareRoot for 2^N and 2^N - 1, 1 <= N <= Double.MAX_EXPONENT", sb.build().collect(Collectors.summingInt(f))); At line 1892 of the current version of MutableBigInteger I changed "if (bitLength() < 63)" to "if (bitLength() <= 63)". I realized that in that case the entire calculation might as well be done in longs so I changed it accordingly. The modified test passes with this new revision. Thanks, Brian On Dec 9, 2015, at 6:11 PM, Joseph D. Darcy <joe.da...@oracle.com> wrote: > New version looks good. > > One more case to try: start with a BigInteger that would overflow to > Double.POSITIVE_INFINITY when the doubleValue method was called. If this case > doesn't take too long to run, it would be a fine additional case to add to > the test. 2^1024 should be fine input value. More precisely, > > (new BigDecimal(Double.MAX_VALUE)).toBigInteger().add(BigInteger.ONE); > > should do the trick. If the code passes with this value, you're okay to push. > Well, while you're at it, might as well verify > > (new BigDecimal(Double.MAX_VALUE)).toBigInteger() > > behaves well too ;-) On Dec 9, 2015, at 6:22 PM, Louis Wasserman <wasserman.lo...@gmail.com> wrote: > Guava's tests check the explicit definition of square root (mentioned by Joe > above) on 2^n +/- 1 for all n up to Double.MAX_EXPONENT + 1, because why not?