[ python-Bugs-1388949 ] Decimal sqrt() ignores rounding

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Bugs item #1388949, was opened at 2005-12-23 12:11
Message generated for change (Comment added) made by facundobatista
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Category: Python Library
Group: None
>Status: Closed
>Resolution: Rejected
Priority: 5
Submitted By: Adam Olsen (rhamphoryncus)
Assigned to: Facundo Batista (facundobatista)
Summary: Decimal sqrt() ignores rounding

Initial Comment:
Decimal Contexts' sqrt() method exhibits the same
rounding behavior irregardless of the rounding parameter.

>>> c = decimal.Context(rounding=decimal.ROUND_CEILING)
>>> f = decimal.Context(rounding=decimal.ROUND_FLOOR)
>>> cs =
decimal.Context(rounding=decimal.ROUND_CEILING, prec=14)
>>> fs = decimal.Context(rounding=decimal.ROUND_FLOOR,
prec=14)
>>> c.sqrt(D(2))
Decimal("1.414213562373095048801688724")
>>> f.sqrt(D(2))
Decimal("1.414213562373095048801688724")
>>> cs.sqrt(D(2))
Decimal("1.4142135623731")
>>> fs.sqrt(D(2))
Decimal("1.4142135623731")

It appears to always round up.


Python 2.4.2 (#2, Nov 20 2005, 17:04:48)
Debian unstable

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>Comment By: Facundo Batista (facundobatista)
Date: 2005-12-24 14:46

Message:
Logged In: YES 
user_id=752496

The rounding setting in the context is not used, always uses
the round-half-even algorithm, as specified in the Decimal
Specification (see
http://www2.hursley.ibm.com/decimal/daops.html#refsqrt).

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