[TUHS] Slashes

Nemo cym224 at gmail.com
Mon Jul 11 00:11:53 AEST 2016


On 9 July 2016 at 09:22, Doug McIlroy <doug at cs.dartmouth.edu> wrote:
> If 19961 is the oldest citation the OED can come up with, "slash"
> really is a coinage of the computer age. Yet the character had
> been in algebra books for centuries. The oral tradition that underlies
> eqn would be the authority for a "solid" name. I suspect, though,
> that regardless of what the algebra books called it, the name
> would be "divided by".

Out of curiosity, I consulted Cajori [1].  All sorts of notations were
used to denote division (including reversed letters) in antiquity
although fractions were commonly denoted by numerator above a
separating line and denominator below.  In 1659, Johann Heinrich Rahn
introduced the symbol ÷ (period above and below a minus sign, Unicode
00F7 -- apologies if the symbol does not display) for division, having
been previously used to indicate subtraction.   In 1684, G.W. Liebniz
introduced ':' for division.  Later authors used both solidus and
reverse-solidus to indicate division.  (Frustratingly, Cajori never
gives a name to the symbol '/'.)

Here is the start of Para. 240 (shades of Algol vs C): "There are
perhaps no symbols which are as completely observant of political
boundaries as are ÷ [Unicode 00F7] and : as symbols for division.  The
former belongs to Great Britain, the British dominions, and the United
States.  The latter belongs to Continental Europe and the
Latin-American countries."  In 1923, the US National Committee on
Mathematical Requirements recommended dropping ÷ (Unicode 00F7) in
favour of the symbol '/' (again nameless).

Bemer, an IBM engineer, argued that the Selectric type ball should be
designed to carry 64 characters required for ASCII, rather than the
typewriter standard 44
(http://www-03.ibm.com/ibm/history/ibm100/us/en/icons/selectric).  The
suggestion was dismissed.  Knuth, in his TeXbook, refers to
"non-mathematical slashes" and entries for virgule and solidus say
"See slash".

[1] A History Of Mathematical Notations Vol I

N.


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