From: Guy Steele (Guy.Steele@sun.com)
Date: Wed Nov 02 2005 - 10:44:40 CST
On Nov 2, 2005, at 1:39 AM, Jukka K. Korpela wrote:
> ... Incidentally, when exponentiation is to be expressed
> compactly in plain text, then I think UPWARDS ARROW U+2191 would
> be a better symbol than circumflex ^ (which was originally taken
> into use in exponential expressions since it can be imagined to be
> a simulation of an upwards arrow).
Agreed. I note, however, that ASCII originally (1963) did have an
"upwards arrow"
character, and a left arrow also. I well remember using Teletype
Model 33
terminals with these characters. There were programming languages
in the 1960s that used left arrow for assignment and/or up arrow for
exponentiation. (Digital Equipment Corporation's FOCAL languages, for
example, which ran on their PDP-8 computers, used = for assignment
but used up arrow for exponentiation.) When ASCII was revised
in 1967, the up arrow was replaced with the circumflex and the
left arrow with an underscore. These at least had some vague visual
similarity to the old characters. The same old software continued
to be used, of course; I also well remember how offended I was
aesthetically when forced to deal with _ as an assignment character
---my code looked terrible.
So I submit that the modern use of circumflex for exponentiation
probably does not stem directly from its visual appearance---rather,
it stems from the legacy of the use of up arrow for exponentiation
in the 1960s and the replacement of this up arrow with the circumflex
in ASCII. That the circumflex has some vague visual similarity to an
up arrow has made its continued use over the years for exponentiation
somewhat palatable.
--Guy Steele
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