[Steven D'Aprano]
> ...
> Will Python always use 64-bit floats?
A CPython "float" is whatever the platform C compiler means by
"double". The C standard doesn't define the size of a double, so
neither does Python define the size of a float.
That said, I don't know of any Python platform to date w
[Bengt Richter]
> I wonder if frexp is always available,
Yes, `frexp` is a standard C89 libm function. Python's `math` doesn't
contain any platform-specific functions.
...
> The math module could also expose an efficient multiply by a power
> of two using FSCALE if the pentium FPU is there.
`l
On Sun, 18 Dec 2005 08:37:40 +, Bengt Richter wrote:
> On Sun, 18 Dec 2005 10:27:16 +1100, Steven D'Aprano <[EMAIL PROTECTED]> wrote:
>
>>On Sat, 17 Dec 2005 09:26:39 +, Bengt Richter wrote:
>>
>>
>>> I wonder if this won't work (for IEEE 754 double that is)
>
On Sun, 18 Dec 2005 10:27:16 +1100, Steven D'Aprano <[EMAIL PROTECTED]> wrote:
>On Sat, 17 Dec 2005 09:26:39 +, Bengt Richter wrote:
>
>
>> I wonder if this won't work (for IEEE 754 double that is)
^^^[1]
>>
>> from math import frexp
>> def next
On Sat, 17 Dec 2005 03:27:11 -0500, Tim Peters wrote:
> While the C99 standard defines such a function (several, actually),
> the C89 standard does not, so Python can't rely on one being
> available. In general, Python's `math` module exposes only standard
> C89 libm functions, plus a few extras
On Sat, 17 Dec 2005 09:26:39 +, Bengt Richter wrote:
> I wonder if this won't work (for IEEE 754 double that is)
>
> from math import frexp
> def nextf(x, y):
> f,e = frexp(x)
> if (f==0.5 or f==-0.5) and x>=y: eps = 2.0**-54
> else: eps = 2.0**-53
> if x else: return (f-
On Sat, 17 Dec 2005 14:23:38 +1100, Steven D'Aprano <[EMAIL PROTECTED]> wrote:
>I'm looking for some way to get the next floating point number after any
>particular float.
>
>(Any mathematicians out there: I am aware that there is no "next real
>number". B
[Steven D'Aprano]
> I'm looking for some way to get the next floating point number after any
> particular float.
...
> According to the IEEE standard, there should be a routine like next(x,y)
> which returns the next float starting from x in the direction of y.
>
> Un
Steven D'Aprano wrote:
> Unless I have missed something, Python doesn't appear to give an interface
> to the C library's next float function. I assume that most C floating
> point libraries will have such a function.
http://www.mkssoftware.com/docs/man3/nextafter.3.asp
--
Robert Kern
[EMAIL PRO
I'm looking for some way to get the next floating point number after any
particular float.
(Any mathematicians out there: I am aware that there is no "next real
number". But floats are not real numbers, they only have a finite
precision.)
According to the IEEE standard, there shou
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