On Feb 10, 5:50 pm, Ben Finney <[EMAIL PROTECTED]> wrote: > Most people would not want this behaviour either:: > > >>> 0.1 > 0.10000000000000001
Sure. And if it weren't for backwards-compatibility and speed issues one could reasonably propose making Decimal the default floating-point type in Python (whilst still giving access to the hardware binary floating point). I dare say that the backwards-compatibility isn't really a problem: I can imagine a migration strategy resulting in Decimal default floats in Python 4.0 ;-). But there are orders-of-magnitude differences in speed that aren't going to be solved by merely rewriting decimal.py in C. I guess it's all about tradeoffs. > But the justification for this violation of surprise is "Python just > does whatever the underlying hardware does with floating-point > numbers". If that's the rule, it shouldn't be broken in the special > case of division by zero. I'm not convinced that this is really the justification, but I'm not quite sure what we're talking about here. The justification for *printing* 0.1000...1 instead of 0.1 has to do with not hiding binary floating-point strangeness from users, since they're eventually going to have to deal with it anyway, and hiding it arguably causes worse difficulties in understanding. The justification for having the literal 0.1 not *be* exactly the number 0.1: well, what are the alternatives? Decimal and Rational are very slow in comparison with float, and historically Decimal wasn't even available until recently. Mark -- http://mail.python.org/mailman/listinfo/python-list
