User talk:Copyeditor42

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Hex exponent notation
Hi. I have a question regarding an old edit of yours where you added information about a hex exponent notation using a "p" letter to denote "*2^". Can you provide additional information where this notation is used or by whom it was proposed? I am aware of a very similar notation using an uppercase "B" for exactly the same purpose, and have also seen implementations (in calculators) using a lowercase "b", but never a "p" (although this would avoid any possible ambiguity with the base of the mantissa). Can you provide a source for this and/or narrow this down in time? Thanks --Matthiaspaul (talk) 23:58, 29 August 2015 (UTC)


 * The "p" notation is required by IEEE standard 754-2008 for floating-point systems. It's also required by the Single Unix Specification (IEEE standard 1003.1, aka. POSIX) for the %a specifier in the printf family of functions.


 * It's been in printf for ages -- at least 20 years for the GNU printf, which may have been the first to introduce the notation (if it was not the 1985 version of IEEE 754).


 * See the POSIX man-page http://pubs.opengroup.org/onlinepubs/9699919799/functions/printf.html for the %a specifier.


 * I have never seen any other hex exponential notation on machines within the last 35 years; and 'b' or 'B' would certainly be ambiguous within the significand.


 * Copyeditor42 (talk) 10:28, 2 September 2015 (UTC)