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
builtin math functions in VB2008. There are numerous builtin
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. It means it will return only positive numbers.
The syntax is
Math. Abs (number)

Example: Private
Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)
Handles Button1.Click Dim Number1, Number2 as Single Number1= TextBox1.Text Number2=Math.Abs(Number1) Label1.Text=Number2 End Sub
If Number1=  100 then Number2=100
* 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
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.