These functions give the obvious hyperbolic functions. They respectively compute the hyperbolic cosine, sine, tangent, and their inverses, arc-cosine, arc-sine, arc-tangent (or area cosine, etc).
cosh(x) sinh(x) tanh(x) acosh(x) asinh(x) atanh(x)
- a numeric or complex vector
Branch cuts are consistent with the inverse trigonometric functions
asin et seq, and agree with those defined in Abramowitz
and Stegun, figure 4.7, page 86. The behaviour actually on the cuts
follows the C99 standard which requires continuity coming round the
endpoint in a counter-clockwise direction.
All are S4 generic functions: methods can be defined
for them individually or via the
Math group generic.
Abramowitz, M. and Stegun, I. A. (1972) Handbook of Mathematical Functions. New York: Dover. Chapter 4. Elementary Transcendental Functions: Logarithmic, Exponential, Circular and Hyperbolic Functions
The logistic distribution function
plogis is a shifted
tanh() for numeric