# R acosh() Function

The acosh() function in R is used to compute the inverse hyperbolic cosine of a number or a numeric vector.

The hyperbolic arccosine is the inverse of the hyperbolic cosine function, which means that acosh(x) = cosh-1(x).

## Syntax

``acosh(x)``

## Parameters

x: It is a numeric value, array, or vector.

## Example 1: Usage of acosh() function

``acosh(1)``

Output

``[1] 0``

If you pass the 0 to the acosh() function, it will return 0.

``acosh(0)``

Output

``[1] 0``

## Example 2: Passing complex value

Define and pass a complex value to the acosh() function.

``````complex_vec <- 8 + 9i

acosh(complex_vec)``````

Output

``[1] 3.181721+0.845865i``

## Example 3: Plotting

``````# Define the domain (from 1 to, say, 5)
x <- seq(1, 5, by = 0.1)

# Compute acosh for these x values
y <- acosh(x)

# Plot the function
plot(x, y,
type = "l", col = "blue",
main = "Plot of acosh(x)", xlab = "x", ylab = "acosh(x)"
)
``````

Output

## Example 4: Passing a vector

``````vec <- c(-1, 0.5, 0, 0.5, 1)

acosh(vec)``````

Output

``````[1] NaN NaN NaN NaN 0
Warning message:
In acosh(rv) : NaNs produced``````

## Example 5: Passing pi

Let’s find the pi constant’s acosh() value.

``acosh(pi)``

Output

``[1] 1.811526``

Let’s see another example of pi.

``acosh(pi / 4)``

Output

``````[1] NaN
Warning message:
In acosh(pi/4) : NaNs produced``````

That is it.