Lesson 14 : Math Functions

In previous lessons, we have learned how to write codes in Visual Basic 2012 that perform arithmetic operations using standard mathematical operators. However, in order to perform more complex mathematical calculations, we need to use the built-in math functions in Visual Basic 2012. There are numerous built-in mathematical functions in Visual Basic 2012 which we will introduce them one by one in this lesson.

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 belong to the Math class. However, not all mathematical 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. ex . For example, Exp(1)=e=2.71828182

The syntax is Math.Exp (number)

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 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 he 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

Rnd is a very useful function in Visual Basic 2012 . We use the Rnd funciton to write code that involves chance and probability. The Rnd function returns a random value between 0 and 1. Random numbers in their original form are not very useful in programming until we convert them to integers. For example, if we need to obtain a random output of 6 integers ranging from 1 to 6, which makes the program behave 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 is the function that 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 here indicates that the Round function belong to the Math class.