On Wednesday, 18 May 2016 at 17:10:25 UTC, Timon Gehr wrote:
It's not just slightly worse, it can cut the number of useful bits in half or more! It is not unusual, I have actually run into those problems in the past, and it can break an algorithm that is in Phobos today!
I wouldn't call that broken. Looking at the hex output by replacing %f with %A in writefln, it appears the only differences in all those results is the last byte in the significand. As Don's talk pointed out, all floating-point calculations will see loss of precision starting there.
In this case, not increasing precision gets the more accurate result, but other examples could be constructed that _heavily_ favor increasing precision. In fact, almost any real-world, non-toy calculation would favor it.
In any case, nobody should depend on the precision out that far being accurate or "reliable."
