ArcTanh[x,y] & Wikipedia.

When I added the definition ArcTanh[x,y]:=Log[(x+y)/SQRT[x^2-y^2]] (due
to KLUELESS, this group, June 2001) to Wikipedia "Hyperbolic-function",
it was deleted as being "not standard" by MACRAKIS, who accused me of
"original research"! Just as ArcTan[-x,-y] differs by Pi/2 from
ArcTan[(-x)/(-y)], the hyperbolic functions differ by i Pi/2, as the
definitions take the quadrant into account. Making trigonometric and
hyperbolic functions of z, rather than adjacent, opposite, &
hypotenuse, seems to be an oversimplification.
(Note that x & y can be complex, and are used as [y,x] in some
conventions.)
Can anyone provide me with evidence (published applications, original
source of the definition, etc.) that the use of two-argument hyperbolic
functions is well-established?
Roger Beresford.
"Veritas vincet fortius." (The greater truth must prevail?)

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