Math Functions

In Visual Basic 2015, many programs require more than simple addition, subtraction, multiplication, and division. You may need to calculate absolute values, powers, logarithms, random numbers, square roots, or rounded values. Instead of writing all these operations manually, you can use built-in math functions.

These functions help you build more powerful applications such as scientific calculators, business tools, financial models, simulations, games, and measurement systems.

The Abs function returns the absolute value of a number. In other words, it removes the negative sign and returns the non-negative magnitude of the number.

Math.Abs(Number)

Example 18.1 uses a text box for input and a label to display the result:

Private Sub BtnComp_Click(sender As Object, e As EventArgs) Handles BtnComp.Click
    LblAbs.Text = Math.Abs(Val(TxtNum.Text))
End Sub

The Val function converts the text entered in the textbox into a numeric value before the absolute value is calculated.

The Exp function returns the exponential value of a number. For example, Exp(1) is equal to the mathematical constant e, which is approximately 2.71828182.

Math.Exp(Number)

Example 18.2:

Private Sub BtnComp_Click(sender As Object, e As EventArgs) Handles BtnComp.Click
    LblExp.Text = Math.Exp(Val(TxtNum.Text))
End Sub

Again, Val is used to convert the input text to a number.

The Fix function removes the decimal part of a number. For positive numbers, it returns the largest integer smaller than the number. For negative numbers, it returns the smallest integer larger than the number.

Fix(Number)

Unlike many other math functions, Fix does not belong to the Math class.

Private Sub BtnComp_Click(sender As Object, e As EventArgs) Handles BtnComp.Click
    LblFixNum1.Text = Fix(Val(TxtPosNum.Text))
    LblFixNum2.Text = Fix(Val(TxtNegNum.Text))
End Sub

The Int function also truncates the decimal portion and returns an integer. However, it always returns the largest integer that is smaller than the original number.

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

This makes Int slightly different from Fix when working with negative numbers.

The Log function returns the natural logarithm of a number.

Math.Log(Number)

Example 18.4:

Private Sub BtnComp_Click(sender As Object, e As EventArgs) Handles BtnComp.Click
    LblLog.Text = Math.Log(Val(TxtNum.Text))
End Sub

Rnd() is a very useful function for generating random values. It returns a random number between 0 and 1. By itself, that is often not very useful, so programmers usually convert the result into integers for practical applications.

VBMath.Rnd() * Number

For example, to simulate a six-sided dice, use:

Int(VBMath.Rnd() * 6) + 1

This produces a random integer between 1 and 6.

Private Sub BtnGen_Click(sender As Object, e As EventArgs) Handles BtnGen.Click
    LblRnd.Text = Int(VBMath.Rnd() * 6) + 1
End Sub

The Rnd() function belongs to the VBMath class in Visual Basic 2015.

The Round function rounds a number to a specified number of decimal places.

Math.Round(Number, m)

This means the number will be rounded to m decimal places. For example:

Math.Round(7.2567, 2) = 7.26

Example 18.6:

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    Label1.Text = Math.Round(Val(TextBox1.Text), 2)
End Sub

The Sqrt function returns the square root of a number.

Math.Sqrt(Number)

Example 18.7:

Private Sub Button4_Click(sender As Object, e As EventArgs) Handles Button4.Click
    MsgBox(Math.Sqrt(400))
End Sub

The result of Math.Sqrt(400) is 20.