Visual Basic 2008 Tutorial
Lesson 14: Functions Part III- Math Functions
We have learned how to Vb2008 can perform arithmetic functions 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. ex . 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
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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.
source : http://www.vbtutor.net/vb2008/vb2008tutor.html
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