[Python-Dev] Expert floats

[Andrew Koenig]

> > Decimal floating-point has almost all the pitfalls of binary
> > floating-point, yet I do not see anyone arguing against decimal
> > floating-point on the basis that it makes the pitfalls less apparent.

> Actually, decimal floating point takes care of two of the pitfalls of
> binary floating point:

> * binary/decimal conversion

> * easily modified precision

> When people are taught decimal arithmetic, they're usually taught the
> problems with it, so they aren't surprised.  (e.g. 1/3)

But doesn't that just push the real problems further into the background,
making them more dangerous? <0.1 wink>

For example, be it, binary or decimal, floating-point addition is still not
associative, so even such a simple computation as a+b+c requires careful
thought if you wish the maximum possible precision.  Why are you not arguing
against decimal floating-point if your goal is to expose users to the
problems of floating-point as early as possible?