# Golang : Calculate half life decay example

My wife is a chemistry lecturer and she was showing her student how to calculate half-life decay of an element. For this tutorial, let's pretend that we are learning chemistry and learn how to calculate half-life decay of an element with a half-life of 25 years in Golang.

Solving half-life problems is focused on using several equations. The order in which you use them depends on **the data given** and **what is being asked**.

For our code example below, we are given:

-An element has a half-life of 25 years.

-The initial amount is 320 grams.

and asked :

-How many grams after 100 years ?

```
package main
import (
"fmt"
"math"
"time"
)
func round(input float64) float64 {
if input < 0 {
return math.Ceil(input - 0.5)
}
return math.Floor(input + 0.5)
}
func halfLifeDecay(startValue int, startTime time.Time, endTime time.Time, halfLifeInSeconds int) float64 {
timeSpan := endTime.Sub(startTime)
x := 2.0
y := timeSpan.Seconds() / float64(halfLifeInSeconds)
value := float64(startValue) / math.Pow(x, y)
// even if everything is gone(decayed)
// the left over is still 1 mathematically and by physics law
if value < 1 {
value += 1
}
value = round(value)
return value
}
func main() {
// From http://www.chemteam.info/Radioactivity/Radioactivity-Half-Life.html
fmt.Println("An element has a half-life of 25 years.")
fmt.Println("The initial amount is 320 grams.")
fmt.Println("How many grams after 100 years ? ")
// Simulate 100 years later
start := time.Date(2000, 11, 10, 20, 34, 58, 651387237, time.UTC)
end := time.Date(2100, 11, 10, 20, 34, 58, 651387237, time.UTC)
fmt.Println("-------------------------------------------------")
// Confirm that we are using the proper start and end dates
years := end.Year() - start.Year()
fmt.Println("Total years : ", years)
// we use 365 days, no leap or astronomical year
halfLifeInSeconds := 25 * (365 * (24 * 3600))
fmt.Println("Half Life in Seconds : ", halfLifeInSeconds)
fmt.Printf("Grams left after %v years is : %v grams.\n", years, halfLifeDecay(320, start, end, halfLifeInSeconds))
}
```

Output:

An element has a half-life of 25 years.

The initial amount is 320 grams.

How many grams after 100 years ?

Total years : 100

Half Life in Seconds : 788400000

Grams left after 100 years is : 20 grams.

If we change the years to 50 instead of 100:

An element has a half-life of 25 years.

The initial amount is 320 grams.

How many grams after 50 years ?

Total years : 50

Half Life in Seconds : 788400000

Grams left after 50 years is : 80 grams.

Happy decaying!

**References:**

https://www.socketloop.com/tutorials/golang-calculate-time-different

Formula from http://www.chemteam.info/Radioactivity/Radioactivity-Half-Life.html

#### Affiliate :

#### Hire Golang Developers

#### See also : Golang : Calculations using complex numbers example

Tags : golang half-life-decay power-of math-pow round

##### By Adam Ng

IF you gain some knowledge or the information here solved your programming problem. Please consider donating to the less fortunate or some charities that you like. Apart from donation, planting trees, volunteering or reducing your carbon footprint will be great too.

#### Advertisement

#### Tutorials

+14k Golang : How to create new XML file ?

+2k Golang : Handle Palindrome string with case sensitivity and unicode

+1.2k Golang : Convert lines of string into list for delete and insert operation

+3.3k Golang : Sort and reverse sort a slice of floats

+3.4k Golang : How to get garbage collection data?

+9.2k Unmarshal/Load CSV record into struct in Go

+18.3k Golang : Read tab delimited file with encoding/csv package

+2.5k PHP : Shuffle to display different content or advertisement

+1.4k PHP : Proper way to get UTF-8 character or string length

+16.2k Find and replace a character in a string in Go

+9.3k Golang : Linked list example

+2.2k Golang : Find age or leap age from date of birth example