On 2/21/07, Timothy Hochberg <[EMAIL PROTECTED]> wrote:
On 2/21/07, Charles R Harris <[EMAIL PROTECTED]> wrote:
>
>
>
> On 2/21/07, Robert Kern < [EMAIL PROTECTED]> wrote:
> >
> > Christopher Barker wrote:
> > > Robert Kern wrote:
> > >> Christopher Barker wrote:
> > >>> I wonder if there are any C math libs that do a better job than
> > you'd
> > >>> expect from standard FP? (short of unlimited precision ones)
> > >> With respect to π and the zeros of sin() and cos()? Not really.
>
>
> <snip>
>
> Well, you can always use long double if it is implemented on your
> > platform. You
> > will have to construct a value for π yourself, though. I'm afraid that
> > we don't
> > really make that easy.
> >
> > --
>
>
> pi = 3. 1415926535 8979323846 2643383279 5028841971 6939937510
> 5820974944 5923078164 0628620899 8628034825 3421170679 8214808651 *...
>
> *
> I dont know what that looks like when converted to long double. Lessee,
>
> In [1]: import numpy
>
> In [2]: pi = numpy.float128(3.1415926535897932384626433832795028841971)
>
I think this is where you go wrong. Your string of digits is first a
python float and *then* is converted to a long double. In the intermediate
stage it gets truncated and you don't get the precision back.
True. But there is missing functionality here.
In [4]: pi = numpy.float128('3.1415926535897932384626433832795028841971')
---------------------------------------------------------------------------
exceptions.TypeError Traceback (most recent
call last)
/home/charris/workspace/microsat/daemon/<ipython console>
TypeError: a float is required
It's somewhat pointless to have a data type that you can't properly
initialize. I think the string value should work, it works for python types.
Chuck
_______________________________________________
Numpy-discussion mailing list
Numpy-discussion@scipy.org
http://projects.scipy.org/mailman/listinfo/numpy-discussion
