On Mon, Nov 1, 2010 at 8:52 AM, Bj Raz <whitequill...@gmail.com> wrote:
> On Nov 1, 2010, at 5:42 AM, Hrvoje Niksic <hnik...@xemacs.org> wrote: > > > Chris Rebert <c...@rebertia.com> writes: > > > >> (2) The underlying double-precision floating-point number only has ~16 > >> decimal digits of precision, so it's pointless to print out "further" > >> digits. > > > > A digression which has nothing to do with Raj's desire for "better > > accuracy"... > > > > Printing out further digits (without quotes) is not pointless if you > > want to find out the exact representation of your number in python's > > floating point, for educational purposes or otherwise. Python has a > > little-known but very instructive method for determining the makeup of a > > float: > > > >>>> 1.1 .as_integer_ratio() > > (2476979795053773, 2251799813685248) > > > > 1.1 is represented with the closest fraction with a power-of-two > > denominator, 2476979795053773/2251799813685248. As is the case with all > > Python floats, this fraction has an exact decimal representation, > > 1.100000000000000088817841970012523233890533447265625. It is not that > > unreasonable to request that the whole number be printed, and python > > will happily oblige: > > > >>>> "%.100g" % 1.1 > > '1.100000000000000088817841970012523233890533447265625' > > > > The digits after the first cluster of zeros are not garbage, at least > > not in the sense of what you get reading uninitialized memory and such; > > they're mathematically precise decimal digits of the number that "1.1" > > has turned into during conversion to float. > > Thank you Chris. > > -- > > http://mail.python.org/mailman/listinfo/python-list > Would "math.fsum" be of any use to me? and what is a good application of the ".as_integer_ratio()" for the out put? Also I really just need the last number that starts to replete at the end of each iteration. Is there a way to isolate that number that repeats a whole bunch of times? Or at least cut off the output when it stops repeating? So I get an output that looks like; "[0, -1.3333333333333333, -1.2444444444444445, -1.2458553791887126, -1.2458468280690504, -1.2458468531272766, -1.2458468530863318, -1.2458468530863729]" or "[-1.2458468530863729]" and not: [0, -1.3333333333333333, -1.2444444444444445, -1.2458553791887126, -1.2458468280690504, -1.2458468531272766, -1.2458468530863318, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729, -1.2458468530863729]. and when I am working with, other numbers; is there a way to get more repetitions if I really need it? Thank you everyone for all your suggestions and help. :)
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