[issue26223] decimal.to_eng_string() does not implement engineering notation in all cases.

[Serge Stroobandt]

New submission from Serge Stroobandt:

In https://docs.python.org/2/library/string.html#formatstrings the proprietary (IBM) specifcation "Decimal Arithmetic Specification" http://www.gobosoft.com/eiffel/gobo/math/decimal/daconvs.html is incorrectly being heralded as "the" specifiaction for engineering notation.

However, upon reading this IBM specifation carefully, one will note that the specifaction itself actually admits not applying the engineering notation in the case of infinite numbers.

An emphasized version of the exact quote accompanied with a discussion can be found here: http://stackoverflow.com/a/17974598/2192488

Correct behaviour for decimal.to_eng_string() would be to equally employ engineering notation in the case of infinite numbers.

I suggest renaming the current behaviour to decimal.to_ibm_string().

References:
http://www.augustatech.edu/math/molik/notation.pdf
https://en.wikipedia.org/wiki/Engineering_notation
https://en.wikipedia.org/wiki/General_Conference_on_Weights_and_Measures
http://www.bipm.org/en/CGPM/db/11/11/

PS: I am a MSc in Electronic Engineering.

----------
components: Extension Modules
files: engineering_notation.pdf
messages: 259047
nosy: Keith.Brafford, eric.smith, ezio.melotti, serge.stroobandt
priority: normal
severity: normal
status: open
title: decimal.to_eng_string() does not implement engineering notation in all cases.
type: behavior
versions: Python 2.7
Added file: http://bugs.python.org/file41730/engineering_notation.pdf

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<http://bugs.python.org/issue26223>
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