On Feb 4, 9:44 pm, Tim Rowe wrote:
> That just leaves me puzzled as to why Mark Summerfield used it instead
> of a check against zero on user input.
No idea: you'd have to ask Mark Summerfield. If there's
an email address published in his book, I'm sure he
wouldn't object to the question.
> So
2009/2/5 Scott David Daniels :
> And, of course he is right (and didn't even whomp on my typo of "makes"
> as "mes in the first line quoted above).
A typo for "makes" didn't bother me. Non-associativity of the real
numbers under addition risked making my whole world fall apart :-)
--
Tim Rowe
I wrote:
> You are missing the whole thing that mes floating point tricky
> The reason it is tough is that addition is not associative in real
> numbers, and associativity is at the core > of a lot of proofs in
> arithmetic (and group theory).
In response to which Tim Rowe wrote:
... Thanks
2009/2/4 Scott David Daniels :
Thanks for that. It makes me feel guilty to point out that:
> addition is not associative in real numbers
should presumably be "addition is not associative in floating point numbers".
--
Tim Rowe
--
http://mail.python.org/mailman/listinfo/python-list
2009/2/4 Mark Dickinson :
> There are many positive floating-point values smaller than
> sys.float_info.epsilon.
>
> sys.float_info.epsilon is defined as the difference between 1.0 and
> the next largest representable floating-point number. On your system,
> the next largest float is almost certa
Tim Rowe wrote:
> I'm reading Mark Summerfield's "Programming Python 3.0" at the moment,
> and I'm puzzled by some of his uses of sys.float_info.epsilon. I
> appreciate the issues of comparing floating point numbers, but I'm
> puzzled by code like:
> ...
> x = float(input(msg))
> if abs
On Feb 4, 7:52 pm, Scott David Daniels wrote:
> You are missing the whole thing that mes floating point tricky.
> I _believe_ that the epsilon is the smallest positive x such that
> 1.0 != 1.0 + x
Nitpick alert: this isn't quite the same thing, since that
definition is affected by rounding.
On Feb 4, 7:18 pm, Tim Rowe wrote:
> I didn't realise that float() could return anything with an absolute
> value less than sys.float_value.epsilon other than 0.0 (which I think
> all representations can represent exactly). What am I missing here?
There are many positive floating-point values sm
Tim Rowe wrote:
I'm reading Mark Summerfield's "Programming Python 3.0" at the moment,
and I'm puzzled by some of his uses of sys.float_info.epsilon. I
appreciate the issues of comparing floating point numbers, but I'm
puzzled by code like:
...
x = float(input(msg))
if abs(x) < sys.fl
