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Diffstat (limited to 'Lib/_pydecimal.py')
-rw-r--r-- | Lib/_pydecimal.py | 99 |
1 files changed, 1 insertions, 98 deletions
diff --git a/Lib/_pydecimal.py b/Lib/_pydecimal.py index 2692f2f..de4561a 100644 --- a/Lib/_pydecimal.py +++ b/Lib/_pydecimal.py @@ -13,104 +13,7 @@ # bug) and will be backported. At this point the spec is stabilizing # and the updates are becoming fewer, smaller, and less significant. -""" -This is an implementation of decimal floating point arithmetic based on -the General Decimal Arithmetic Specification: - - http://speleotrove.com/decimal/decarith.html - -and IEEE standard 854-1987: - - http://en.wikipedia.org/wiki/IEEE_854-1987 - -Decimal floating point has finite precision with arbitrarily large bounds. - -The purpose of this module is to support arithmetic using familiar -"schoolhouse" rules and to avoid some of the tricky representation -issues associated with binary floating point. The package is especially -useful for financial applications or for contexts where users have -expectations that are at odds with binary floating point (for instance, -in binary floating point, 1.00 % 0.1 gives 0.09999999999999995 instead -of 0.0; Decimal('1.00') % Decimal('0.1') returns the expected -Decimal('0.00')). - -Here are some examples of using the decimal module: - ->>> from decimal import * ->>> setcontext(ExtendedContext) ->>> Decimal(0) -Decimal('0') ->>> Decimal('1') -Decimal('1') ->>> Decimal('-.0123') -Decimal('-0.0123') ->>> Decimal(123456) -Decimal('123456') ->>> Decimal('123.45e12345678') -Decimal('1.2345E+12345680') ->>> Decimal('1.33') + Decimal('1.27') -Decimal('2.60') ->>> Decimal('12.34') + Decimal('3.87') - Decimal('18.41') -Decimal('-2.20') ->>> dig = Decimal(1) ->>> print(dig / Decimal(3)) -0.333333333 ->>> getcontext().prec = 18 ->>> print(dig / Decimal(3)) -0.333333333333333333 ->>> print(dig.sqrt()) -1 ->>> print(Decimal(3).sqrt()) -1.73205080756887729 ->>> print(Decimal(3) ** 123) -4.85192780976896427E+58 ->>> inf = Decimal(1) / Decimal(0) ->>> print(inf) -Infinity ->>> neginf = Decimal(-1) / Decimal(0) ->>> print(neginf) --Infinity ->>> print(neginf + inf) -NaN ->>> print(neginf * inf) --Infinity ->>> print(dig / 0) -Infinity ->>> getcontext().traps[DivisionByZero] = 1 ->>> print(dig / 0) -Traceback (most recent call last): - ... - ... - ... -decimal.DivisionByZero: x / 0 ->>> c = Context() ->>> c.traps[InvalidOperation] = 0 ->>> print(c.flags[InvalidOperation]) -0 ->>> c.divide(Decimal(0), Decimal(0)) -Decimal('NaN') ->>> c.traps[InvalidOperation] = 1 ->>> print(c.flags[InvalidOperation]) -1 ->>> c.flags[InvalidOperation] = 0 ->>> print(c.flags[InvalidOperation]) -0 ->>> print(c.divide(Decimal(0), Decimal(0))) -Traceback (most recent call last): - ... - ... - ... -decimal.InvalidOperation: 0 / 0 ->>> print(c.flags[InvalidOperation]) -1 ->>> c.flags[InvalidOperation] = 0 ->>> c.traps[InvalidOperation] = 0 ->>> print(c.divide(Decimal(0), Decimal(0))) -NaN ->>> print(c.flags[InvalidOperation]) -1 ->>> -""" +"""Python decimal arithmetic module""" __all__ = [ # Two major classes |