Re: float point properties access

[Robin Becker]

Robin Becker wrote:
Neal D. Becker wrote:
Is there a way in python to access properties of floats?  I need 
something
equiv to C DBL_EPSILON defined in <float.h>.


you could try the traditional algorithm
 >>> def dbl_epsilon():
...     n = 0
...     while 1:
...         e = 1.0/2**n
...         if (1.0+e==1.0): break
...         n += 1
...         pe = e
...     return pe
...
 >>> print dbl_epsilon()
2.22044604925e-016
 >>>
on looking further I find my 'traditional' algorithm is actually 
something like this

def dbl_epsilon(_eps=[]):
        if not _eps:
                etop = 1.0
                ebot = 0.0
                eps = ebot+(etop-ebot)/2.0
                while eps!=ebot and eps!=etop:
                        epsp1 = 1.0 - eps
                        if epsp1<1.0: etop = eps
                        else: ebot = eps
                        eps = ebot+(etop-ebot)/2.0
                _eps.append(etop)
                assert (1.0-etop)<1.0 and (1.0-ebot)==1.0, 'Error in epsilon 
calculation'
        return _eps[0]
print dbl_epsilon()
which gives 5.55111512313e-017
-senility is making me stupidly yrs-
Robin Becker
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