[docs] [issue21510] fma documentation should provide better example.

[Jayanth Koushik]

New submission from Jayanth Koushik:

The documentation for decimal.fma provides an example which fails to illustrate the most important feature of the function i.e. single rounding. In fact:

    Decimal(2).fma(3, 5) == Decimal(2)*3 + 5

An example such as this would make it much more clear:

    >>> getcontext().prec = 2
    >>> getcontext().rounding = ROUND_DOWN
    >>> Decimal('1.5')*Decimal('1.5') + Decimal('1.05')
    Decimal('3.2')
    >>> Decimal('1.5').fma(Decimal('1.5'), Decimal('1.05'))
    Decimal('3.3')

----------
assignee: docs at python
components: Documentation
messages: 218592
nosy: docs at python, jayanthkoushik
priority: normal
severity: normal
status: open
title: fma documentation should provide better example.
type: enhancement
versions: Python 2.7, Python 3.1, Python 3.2, Python 3.3, Python 3.4, Python 3.5

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue21510>
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