How to Use the exp() Function in R


Often you may want to calculate the exponential of a number in R.

When we use the term exponential, we refer to taking the value e in mathematics (which has a value of 2.71828…) and raising it to the power of our specific number.

For example, to take the exponential of the number 5 we would write it as e5, which turns out to be 148.4132.

To calculate the exponential of a number in R, you can use the exp() function which uses the following syntax:

exp(x)

where:

  • x: The number of interest

This function is built into base R, which means you don’t need to install or load any external packages to use the function.

The following example shows how to use the exp() function in practice in R to calculate the exponential of a number.

Example: How to Use the exp() Function in R

Suppose that you would like to calculate the exponential of the number 5 in R.

You can use the following syntax with the exp() function to do so:

#calculate exponential of the number 5
exp(5)

[1] 148.4132

This returns a value of 148.4132, which matches the value that we calculated in the intro of this article.

Note that you can also use the exp() function to calculate the exponential of all values in a given vector.

For example, we can use the following syntax to create a vector named my_vector with values ranging from 1 to 10 and then use the exp() function to calculate the exponential of each value in the vector:

#create vector
my_vector <- c(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)

#calculate exponential of each number in vector
exp(my_vector)

 [1]     2.718282     7.389056    20.085537    54.598150   148.413159
 [6]   403.428793  1096.633158  2980.957987  8103.083928 22026.465795

The exp() function returns the exponential of each value in the vector.

For example, we can see:

  • The exponential of 1 is 2.718282.
  • The exponential of 2 is 7.389056.
  • The exponential of 3 is 20.085537.
  • The exponential of 4 is 54.598150.

And so on.

Note that we can use the round() function if we’d like to round the number of decimal places to a specific number as well.

For example, we can use the following syntax to calculate the exponential of each value in the vector and round the resulting values to two decimal places:

#create vector
my_vector <- c(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)

#calculate exponential of each number in vector and round results
round(exp(my_vector), 2)

 [1]     2.72     7.39    20.09    54.60   148.41   403.43  1096.63  2980.96
 [9]  8103.08 22026.47

We can see that each value in the output has been rounded to exactly two decimal places, just as we specified.

It’s worth noting that the opposite of calculating the exponential of a number is calculating the log of the number.

Thus, if we calculate the log of a number using the log() function in R and then calculate the exponential using the exp() function then we will simply end up with the number that we started with:

#create vector
my_vector <- c(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)

#calculate log and then exponential of each number in vector
round(exp(log(my_vector)))

 [1]  1  2  3  4  5  6  7  8  9 10

Keep this in mind when using the log() and exp() functions in R.

Additional Resources

The following tutorials explain how to perform other common tasks in R:

How to Apply Function to Each Row in R
How to Find Column with Max Value for Each Row in R
How to Use the gregexpr() Function in R

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