The **`imag`** function in Golang is a built-in function that extracts the imaginary part of a given complex number.

The process is illustrated below:

The prototype of the `imag` function is shown below:

```Go
func imag(c ComplexType) FloatType
```

<h2>Parameters</h2>

The `imag` function takes a single mandatory parameter in the form of a `ComplexType` object.

<h2>Return value</h2>

The `imag` function returns a `FloatType` object that represents the imaginary part of the complex number provided as a parameter. 

If the given complex number is a `complex64` object, then the `imag` function returns a `float32` object. If the given complex number is a `complex128` object, then the `imag` function returns a `float64` object.

<h2>Example</h2>

The code below shows how the `imag` function works in Golang:

package main

import (
	"fmt"
)

func main() {

  // initializing complex values
	a := complex(15, 2)
	b := complex (-5, 4)
	
  // extracting imaginary parts
	fmt.Println("The imaginary part of", a , "is", imag(a))
	fmt.Println("The imaginary part of", b , "is", imag(b))
	
}


<h2>Explanation</h2>

The `complex` function in lines $10$ and $11$ initializes a complex object based on the values provided for the real and imaginary parts. 

The `imag` function in lines $14$ and $15$ proceeds to extract the imaginary part of each complex object, i.e., $2$ and $4$, respectively. The extracted imaginary values are then output. 

What is the imag function in Golang?

The imag function in Golang retrieves the imaginary part of a complex number, returning float32 for complex64 and float64 for complex128 inputs.