At 12:52 PM 11/30/2006, Dick Moores wrote:
>At 11:19 PM 11/27/2006, Dick Moores wrote:
> >I just dug this Tim Smith creation out of the Tutor archive.
> >
> >def round_to_n(x, n):
> > """
> > Rounds float x to n significant digits, in scientific notation.
> > Written by Tim Peters. See his Tutor list post of 7/3/04 at
> > http://mail.python.org/pipermail/tutor/2004-July/030324.html
> > """
> > if n < 1:
> > raise ValueError("number of significant digits
> must be >= 1")
> > return "%.*e" % (n-1, x)
> >
> >Thought others might find it of use.
> >
> >Dick Moores
>
>I've run into the limitation on the size of an int that can be
>converted to a float.
I back with this topic.
I'd completely forgotten that I had written numberRounding(), which
doesn't suffer from that limitation:
def numberRounding(n, significantDigits=4):
import decimal
def d(x):
return decimal.Decimal(str(x))
decimal.getcontext().prec = significantDigits
return d(n)/d(1)
Thus,
>>> n = 2**2000
>>> print numberRounding(n,6)
1.14813E+602
BTW the last line of numberRounding() seems strange (even though it
works)? Why wouldn't "return d(n)" do the job?
Thanks,
Dick Moores
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