On 9/4/06, Sebastian Haase <haase@msg.ucsf.edu> wrote:
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]

That does look like a bug.

>>> array([66]).round(-1)
array([60])
>>> array([66.]).round(-1)
array([ 70.])

I suspect it is related to the integer data type of the first example. The code probably does something like this:

round(66/10)*10

and 66/10 == 6 in integer arithmetic.

Chuck
 

  >>> N.array([66.2]).round(-1)
[ 70.]

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

Don't recall.

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 ...)

I have improved the document strings and the example at scipy.org.

Chuck