Le funzioni iperboliche

sinh(x) = (exp(x)-exp(-x))/2,  cosh(x) = (exp(x)+exp(-x))/2

source("http://macosa.dima.unige.it/r.R")
# a sinistra
PLANE(-4,4, -4,4)
h <- function(x,y) x^2-y^2; CURVE(h, 0)
f <- function(x,y) x^2-y^2-1
CURVE(f,"seagreen")
# al centro
x <- function(t) cosh(t); y <- function(t) sinh(t)
param(x,y, -3,3, "red")
# a destra
PLANE(-4,4, -4,4)
graph1(sinh,-4,4, "red")
graph1(cosh,-4,4, "blue")