R atan() Function

The atan() function in R is used to calculate a number’s arc tangent (inverse tangent).

Syntax

atan(number)

Parameters

number: It’s a number as a numeric value.

Return value

The domain of this function is all real numbers, and it returns values in the range -π/2 to π/2 radians.

Example 1: Basic usage

Visual representation of r atan() function

num1 <- -1
num2 <- 0.5
num3 <- 0

atan(num1)
atan(num2)
atan(num3)

Output

[1] -0.7853982
[1] 0.4636476
[1] 0

Example 2: Using vector

Using atan() function with a vector

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

atan(vec)

Output

[1] -0.7853982 0.4636476 0.0000000 0.4636476 0.7853982

Example 3: Passing a pi

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

atan(pi)

atan(pi / 4)

Output

[1] 1.262627

[1] 0.6657738

Example 4: Plotting

dt <- seq(-1, 1, by = 0.01)

plot(dt, atan(x), typ = "l", col = "red")

abline(v = 0, lty = 6, col = "blue")

Output

R atan() Function

We created a sequence dt from -1 to 1 in increments of 0.01 and then generated a line plot of the arctangent function (atan(dt)) over this range, with the red curve.

In the next step, we added a dashed blue vertical line at x = 0 to the plot using abline(), which may serve as an axis or reference line.

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