Hyperbolic Trigonometric Functions
DESCRIPTION:
Returns the hyperbolic sine, hyperbolic cosine or hyperbolic tangent transformation of a numeric or complex valued object.
USAGE: 
cosh(x)
sinh(x)
tanh(x)
REQUIRED ARGUMENTS:
x:
numeric (in radians), or complex object. Missing values (NAs) are allowed.
VALUE:
data transformed by the specified hyperbolic trigonometric function, with attributes preserved.
DETAILS:
Missing values in the input create missing values in the output.

These are members of the Math group of generic functions.

See section 5.1.5 of Becker, Chambers and Wilks for details on domains and branch cuts in the case of complex arguments.

SEE ALSO:
cos , acosh .
EXAMPLES: 
1/tanh(x) # hyperbolic cotangent of x


# be sure you have an open graphics window
plot(sinh(sort(rnorm(500))))
plot(cosh(sort(rnorm(500))))
plot(tanh(sort(rnorm(500))))