Re: Smallest float different from 0.0?

2009-09-07 Thread Steven D'Aprano
On Mon, 07 Sep 2009 08:23:58 -0700, Mark Dickinson wrote: > There's sys.float_info.min: > import sys sys.float_info > sys.float_info(max=1.7976931348623157e+308, max_exp=1024, > max_10_exp=308, min=2.2250738585072014e-308, min_exp=-1021, > min_10_exp=-307, dig=15, mant_dig=53, epsilon=2

Re: Smallest float different from 0.0?

2009-09-07 Thread Steven D'Aprano
On Mon, 07 Sep 2009 08:23:58 -0700, Mark Dickinson wrote: > On Sep 7, 3:47 pm, kj wrote: >> Is there some standardized way (e.g. some "official" module of such >> limit constants) to get the smallest positive float that Python will >> regard as distinct from 0.0? >> >> TIA! >> >> kj > > There's

Re: Smallest float different from 0.0?

2009-09-07 Thread Mark Dickinson
On Sep 7, 5:08 pm, kj wrote: > Hmmm.  This close-to-the-metal IEEE stuff make a "HERE BE DRAGONS!" > alarms go off in my head...  (What's up with that correction by 1 > to sys.float_info.mant_dig?  Or, probably equivalently, why would > sys.float_info.min_exp (-1021) be off by 1 relative to log2 o

Re: Smallest float different from 0.0?

2009-09-07 Thread kj
In Mark Dickinson writes: >The smallest positive subnormal value >is usually 2**-1074. If you want something that would still work >if Python ever switched to using IEEE 754 binary128 format (or some >other IEEE 754 format), then >sys.float_info.min * 2**(1-sys.float_info.mant_dig) Hmmm. Th

Re: Smallest float different from 0.0?

2009-09-07 Thread kj
In Mark Dickinson writes: >On Sep 7, 3:47=A0pm, kj wrote: >> Is there some standardized way (e.g. some "official" module of such >> limit constants) to get the smallest positive float that Python >> will regard as distinct from 0.0? >> >> TIA! >> >> kj >There's sys.float_info.min: impor

Smallest float different from 0.0?

2009-09-07 Thread Xavier Ho
This topic came up before. =] See below. Not sure how 'standardised' this is, though. Double precision: >>> import struct >>> struct.unpack('d', struct.pack('Q', 1))[0] 4.9406564584124654e-324 Float precision: >>> struct.unpack('f', struct.pack('L', 1))[0] 1.4012984643248171e-45 Cheers, Xavier

Re: Smallest float different from 0.0?

2009-09-07 Thread Mark Dickinson
On Sep 7, 3:47 pm, kj wrote: > Is there some standardized way (e.g. some "official" module of such > limit constants) to get the smallest positive float that Python > will regard as distinct from 0.0? > > TIA! > > kj There's sys.float_info.min: >>> import sys >>> sys.float_info sys.float_info(ma

Re: Smallest float different from 0.0?

2009-09-07 Thread Diez B. Roggisch
Paul McGuire wrote: > On Sep 7, 9:47 am, kj wrote: >> Is there some standardized way (e.g. some "official" module of such >> limit constants) to get the smallest positive float that Python >> will regard as distinct from 0.0? >> >> TIA! >> >> kj > > You could find it for yourself: > for i

Re: Smallest float different from 0.0?

2009-09-07 Thread Paul McGuire
On Sep 7, 9:47 am, kj wrote: > Is there some standardized way (e.g. some "official" module of such > limit constants) to get the smallest positive float that Python > will regard as distinct from 0.0? > > TIA! > > kj You could find it for yourself: >>> for i in range(400): ...if 10**-i == 0:

Smallest float different from 0.0?

2009-09-07 Thread kj
Is there some standardized way (e.g. some "official" module of such limit constants) to get the smallest positive float that Python will regard as distinct from 0.0? TIA! kj -- http://mail.python.org/mailman/listinfo/python-list