[Numpy-discussion] bug in round with negative number of decimals

Sebastian Haase haase at msg.ucsf.edu
Mon Sep 4 14:03:51 CDT 2006


Paulo J. S. Silva wrote:
> Once again, the information that singed zero is part of IEEE standard is
> in the paper I cited in my last message.
> 
> It is very important to be able to compute the sign of an overflowed
> quantity in expressions like 1/x when x goes to zero.
> 
> Best,
> 
> Paulo
Hi,

This is all very interesting ( and confusing (to me, maybe others) at 
the same time ...) ...

Question 0: Are you sure this is not a bug ?
  >>> N.array([66]).round(-1)
[60]
  >>> N.array([66.2]).round(-1)
[ 70.]

Question 1: Was this way of round already in Numeric and /or in numarray ?

Question 2: Does this need to be better documented (complete and 
corrected(!) docstrings - maybe a dedicated wiki page )  !?
This is related to "How does Matlab or IDL or others do rounding ?" - 
This would at least determine how many people would be surprised by this.
(I would say that *if* Matlab rounds the same way, we might need less 
documentation ...)

Thanks,
Sebastian Haase




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