Visual Basic 2008 Mortgage Calculator

[Peanut373]

Hi, I have a school project in which I must complete a mortgage calculator in Visual Basic. I have made the calculator, and it displays the result, but the only issue is that the value is incorrect. I am new to programming, so maybe someone could help me. Here is my code.

Public Class Form1
Dim InitialAmount, DownPayment, Interest, PaymentPeriod, Payment As Double
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
InitialAmount = Val(TextBox1.Text)
DownPayment = Val(TextBox2.Text)
Interest = Val(TextBox3.Text)
PaymentPeriod = Val(TextBox4.Text)
Payment = Val(TextBox5.Text)

TextBox5.Text = Pmt(Interest, PaymentPeriod * 48, -InitialAmount)
End Sub
End Class

[vb5prgrmr]

Wrong forum, you need the .NET forum...

[Hack]

Moved From Classic VB

The value is incorrect how?

[Peanut373]

Moved From Classic VB

The value is incorrect how?

For example, if I am supposed to recieve a monthly payment of $699.21, my payment on my calculator will say $750. It is usually about $50 off from the appropriate amount. Additionally, does someone know how I could incorporate down payment into the pmt formula?

[Hack]

Walk me through the process.

You have these textboxes:

Textbox1.Text
Textbox2.Text
Textbox3.Text
Textbox4.Text
Textbox5.Text

You have these variables:

InitialAmount
DownPayment
Interest
PaymentPeriod
Payment

You are doing this with them

InitialAmount = Val(TextBox1.Text)
DownPayment = Val(TextBox2.Text)
Interest = Val(TextBox3.Text)
PaymentPeriod = Val(TextBox4.Text)
Payment = Val(TextBox5.Text)

Now, I have $699.21 - what do I do with it? What textbox does it go in, and what happens to it after I put it there? How does your calculator arrive at $750? What is the math function that is performed on my $699.21?

[Peanut373]

Walk me through the process.

You have these textboxes:

Textbox1.Text
Textbox2.Text
Textbox3.Text
Textbox4.Text
Textbox5.Text

You have these variables:

InitialAmount
DownPayment
Interest
PaymentPeriod
Payment

You are doing this with them

InitialAmount = Val(TextBox1.Text)
DownPayment = Val(TextBox2.Text)
Interest = Val(TextBox3.Text)
PaymentPeriod = Val(TextBox4.Text)
Payment = Val(TextBox5.Text)

Now, I have $699.21 - what do I do with it? What textbox does it go in, and what happens to it after I put it there? How does your calculator arrive at $750? What is the math function that is performed on my $699.21?

When the result is calculated, it is displayed as TextBox5.Text. The formula I am using to calculate the monthly payment is:

TextBox5.Text = Pmt(Interest, PaymentPeriod * 48, -InitialAmount)

Since I am new to programming, I doubt this Pmt function is entirely correct, I just can't find what is wrong with it that always gives me a wrong result.