To calculate the inverse sine value of the input numeric value in R, use the asin() function.

## asin in R

The asin() is a built-in R trigonometric function that computes the sine inverse of the given value; the returned angle is in the range -pi/2 through pi/2. The asin() method accepts vectors and returns the inverse of sine value.

**Syntax**

`asin(x)`

**Parameters**

The asin() function takes a column to compute on.

**Example**

Define two vectors and pass them to the asin() function.

```
v1 <- -1
v2 <- 0.5
asin(v1)
asin(v2)
```

**Output**

```
[1] -1.570796
[1] 0.5235988
```

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

`v3 <- 0`

**Output**

`[1] 0`

**Plot the asin() function to a graph**

We can use the seq() function to create a series of values and pass that to the plot() function, which will create a line chart.

```
dt <- seq(-1, 1, by = 0.05)
plot(dt, asin(dt), typ = "l", col = "red")
abline(v = 0, lty = 6, col = "blue")
```

**Output**

**Applying asin() function to a Vector**

To define a Vector in R, use the c() function. Then pass that vector to the asin() function.

```
rv <- c(-1, 0.5, 0, 0.5, 1)
asin(rv)
```

**Output**

`[1] -1.5707963 0.5235988 0.0000000 0.5235988 1.5707963`

**Passing a pi to the asin() function**

The **pi **is an inbuilt constant in R programming, and its value is **3.141593**.

Let’s find the pi constant’s **asin()** value.

`asin(pi)`

**Output**

```
[1] NaN
Warning message:
In asin(pi) : NaNs produced
```

You can see that it returns NaN(not a number) in the output.

Let’s see another example of pi.

`asin(pi / 4)`

**Output**

`[1] 0.9033391`

That is it for this tutorial.

**See also**

Krunal Lathiya is an Information Technology Engineer by education and web developer by profession. He has worked with many back-end platforms, including Node.js, PHP, and Python. In addition, Krunal has excellent knowledge of Data Science and Machine Learning, and he is an expert in R Language. Krunal has written many programming blogs, which showcases his vast expertise in this field.