Google Timeline lists a reference back in 1631, by an English mathematician Richard Norwood, but that link is actually referring to trigonometric functions. The second reference in Timeline (

*A History of Mathematical Notations: Notations Mainly in Higher Mathematics*by Florian Cajori) says that the hyperbolic functions were first used by Vincenzo Riccati in 1757, but he used the notation "Sh." for hyperbolic sine and "Ch." for hyperbolic cosine. Lambert is said to have invented the

*notation*that we now use for these functions (sinh,cosh,tanh) in 1768. However, several other notations were used for these functions well into the 1900s.

So, we can take away from this that

(a) Wikipedia is not to be trusted, even in math;

(b) mathematical notation is all over the place; and

(c) inventing good notation for a concept will make you as famous as the people who invented the actual concept.

## 1 comment:

Incidentally, the reason they are "Hyperbolic" is because of you plot (cosh(t),sinh(t)) for real values of t, the graph is a hyperbola.

Post a Comment