approxEqual() has fooled me for a long time...

[Andrei Alexandrescu]

On 10/20/10 10:52 CDT, Don wrote:
> I don't think it's possible to have a sensible default for absolute
> tolerance, because you never know what scale is important. You can do a
> default for relative tolerance, because floating point numbers work that
> way (eg, you can say they're equal if they differ in only the last 4
> bits, or if half of the mantissa bits are equal).
>
> I would even think that the acceptable relative error is almost always
> known at compile time, but the absolute error may not be.

I wonder if it could work to set either number, if zero, to the smallest 
normalized value. Then proceed with the feqrel algorithm. Would that work?

Andrei