**[Lesson 13] **<< **[CONTENTS] >> [Lesson 15]**

## What are Math Functions

Math functions in VB programming are functions that process one or more numbers and return a value. They are no different functions in mathematics. Though we can create customized math functions, we can save time by using a score of built-in math functions in Visual Basic 2010.

### 14.1 The Abs function

The Abs function returns the absolute value of a given number.The syntax is

Math. Abs (number)

* The Math keyword here indicates that the Abs function belongs to the Math class. However, not all math functions belong to the Math class.

### 14.2 The Exp function

The Exp of a number x is the exponential value of x, i.e. e^{x}.

The syntax is:

Math.Exp (number)

For example,

Exp(1)=e=2.71828182

#### Example 14.1

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Dim num1, num2 As Single num1 = TextBox1.Text num2 = Math.Exp(num1) Label1.Text = num2 End Sub

### 14.3 The Fix Function

The Fix function truncates the decimal part of a positive number and returns the largest integer smaller than the number. However, when the number is negative, it will return the smallest integer larger than the number. For example, Fix(9.2)=9 but Fix(-9.4)=-9

#### Example 14.2

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Dim num1, num2 As Single num1 = TextBox1.Text num2 = Fix(num1) Label1.Text = num2 End Sub

### 14.4 The Int Function

The Int is a function that converts a number into an integer by truncating its decimal part and the resulting integer is the largest integer that is smaller than the number. For example

Int(2.4)=2, Int(6.9)=6 , Int(-5.7)=-6, Int(-99.8)=-100

### 14.5 The Log Function

The Log function is the function that returns the natural logarithm of a number. For example, Log(10)=2.302585

#### Example 14.3

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Dim num1, num2 As Single num1 = TextBox1.Text num2 = Math.Log(num1) Label1.Text = num2 End Sub

* The logarithm of num1 will be displayed on label1

### 14.6 The Rnd( ) Function

The Rnd function returns a random value between 0 and 1. Random numbers often need to be converted into integers in programming. For example, if we wish to obtain a random output of 6 integers ranging from 1 to 6, which makes the program behaves like a virtual dice, we need to convert the random numbers to integers using the formula Int(Rnd*6)+1.

#### Example 14.4

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Dim num as integer Num=Int(Rnd()*6)+1 Label1.Text=Num End Sub

In this example, Int(Rnd*6) will generate a random integer between 0 and 5 because the function Int truncates the decimal part of the random number and returns an integer. After adding 1, you will get a random number between 1 and 6 every time you click the command button. For example, let say the random number generated is 0.98, after multiplying it by 6, it becomes 5.88, and using the integer function Int(5.88) will convert the number to 5, and after adding 1 you will get 6.

### 14.7 The Round Function

The Round function rounds up a number to a certain number of decimal places. The syntax is Round (n, m) which means to round a number n to m decimal places. For example,

Math.Round (7.2567, 2) =7.26

#### Example 14.5

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Dim num1, num2 As Single num1 = TextBox1.Text num2 = Math.Round(num1, 2) Label1.Text = num2 End Sub

* The Math keyword indicates that the Round function belongs to the Math class.