>>> def min_max(seq):
...     it = iter(seq)
...     emin = emax = next(it, None)
...     for e in it:
...         if e < emin:
...             emin = e
...         if e > emax:
...             emax = e
...     return [emin, emax]
... 
>>> min_max([-0.1234567898765431, 15, -0.1234567898765432])
[-0.1234567898765432, 15]
>>>