[Python-Dev] Expert floats (original) (raw)

Andrew Koenig ark-mlist at att.net
Wed Mar 31 14:02:42 EST 2004

> 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?

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