# Visual Basic 2008 Tutorial

Lesson 14:
Functions Part III- Math Functions

We have learned how to create VB2008
programs that can perform arithmetic operations using standard mathematical operators.
However, for more complex mathematical calculations, we need to use the
built-in math functions in VB2008. There are numerous built-in
mathematical functions in Visual Basic which we will introduce them one
by one.

**14.1 The Abs function**

The Abs return 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. e^{x }. For example,
Exp(1)=e=2.71828182

The syntax is **Math.Exp (number)**

Example:

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 truncate 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:

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:

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 is
very useful when we deal with the concept of 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:**

Private
Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)
Handles Button1.Click

Dim num as integer

Randomize( )

Num=Int(Rnd()*6)+1

Label1.Text=Num

End Sub

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**
**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 Format 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

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.

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