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# What is the Expm1 function in Golang?

Faraz Karim

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The Go programming language uses the Expm1 function to find the value of $e$ raised to the power equaling the input $x$, minus $1$. This is the same as $e^x$ -1, where $x$ is the input.

To use this function, you must import the math package in your file and access the Expm1 function within it using the . notation (math.Expm1). Here, Expm1 is the actual function, while math is the Go package that stores the definition of this function.

## Function definition

The definition of the Expm1 function inside the math package is:

## Parameters

The Expm1 function takes a single argument of type float64. This argument represents the number $x$ in the formula $e^x$ -1.

## Return value

The Expm1 function returns a single value of type float64, which results from raising $e$ to the power of $x$, minus $1$ ($x$ being the input float64).

An exception to the above statements is when you pass something that is positive infinity, negative infinity, or NAN as an argument:

• +Inf: If the argument has a positive infinite value, the return value will be exactly the same as the argument, i.e., +Inf.

• -Inf: If the argument has a negative infinite value, the return value will be -1.

• NAN: If a NAN argument is passed, the return value is also NAN.

## Examples

Following is a simple example where we find out the Expm1 value of 5:

package main
import (
"fmt"
"math"
)
func main() {
x := 5.0
y := math.Expm1(x)
fmt.Print(x, "'s exponential value minus 1 is ", y)
}

The following example shows how the Expm1 function handles infinite valued arguments, for which we use the Inf function:

The Inf function returns an infinite value with a sign matching the sign of the argument that it is given.

package main
import (
"fmt"
"math"
)
func main() {
x := math.Inf(-1)
y := math.Expm1(x)
fmt.Print(x, "'s exponential value minus 1 is ", y)
fmt.Print( "\n")
a := math.Inf(1)
b := math.Expm1(a)
fmt.Print(a, "'s exponential value minus 1 is ", b)
}

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CONTRIBUTOR

Faraz Karim