On Wed, Aug 18, 2010 at 11:07 AM, David Cournapeau <[email protected]> wrote: > On Wed, Aug 18, 2010 at 11:52 PM, <[email protected]> wrote: >> On Wed, Aug 18, 2010 at 10:36 AM, Charles R Harris >> <[email protected]> wrote: >>> >>> >>> On Wed, Aug 18, 2010 at 8:25 AM, Colin Macdonald <[email protected]> >>> wrote: >>>> >>>> On 08/18/10 15:14, Charles R Harris wrote: >>>> > However, the various constants supplied by numpy, pi and such, are >>>> > full precision. >>>> >>>> no, they are not. My example demonstrated that numpy.pi is only >>>> double precision. >>>> >>> >>> Hmm, the full precision values are available internally but it looks like >>> they aren't available to the public. I wonder what the easiest way to >>> provide them would be? Maybe they should be long double types by default? >> >> playing with some examples, I don't seem to be able to do anything >> with longdouble on win32, py2.5 > > For all practical purposes, double == long double on windows: although > some compilers support the intel long format or even quadd precision, > the MSVC runtime does not (so you cannot print, scan, etc... making > them useless).
Thanks for the info, I can stop playing Josef > > cheers, > > David >> >>>>> np.array([3141592653589793238L], np.int64).astype(np.longdouble)[0] >> 3141592653589793300.0 >>>>> np.array([3141592653589793238L], np.int64).astype(float)[0] >> 3.1415926535897933e+018 >>>>> 1./np.array([np.pi],np.longdouble)[0] - 1/np.pi >> 0.0 >>>>> 1./np.array([np.pi],np.longdouble)[0] >> 0.31830988618379069 >> >> and it doesn't look like it's the print precision >>>>> 1./np.array([np.pi],np.longdouble)[0]*1e18 >> 318309886183790720.0 >>>>> 1./np.array([np.pi],float)[0]*1e18 >> 3.1830988618379072e+017 >> >> >> type conversion and calculations seem to go through float >> >> Josef >> >>> >>> Chuck >>> >>> >>> _______________________________________________ >>> NumPy-Discussion mailing list >>> [email protected] >>> http://mail.scipy.org/mailman/listinfo/numpy-discussion >>> >>> >> _______________________________________________ >> NumPy-Discussion mailing list >> [email protected] >> http://mail.scipy.org/mailman/listinfo/numpy-discussion >> > _______________________________________________ > NumPy-Discussion mailing list > [email protected] > http://mail.scipy.org/mailman/listinfo/numpy-discussion > _______________________________________________ NumPy-Discussion mailing list [email protected] http://mail.scipy.org/mailman/listinfo/numpy-discussion
