Mathematical and Business Functions

1. Mathematical and Business Functions Chapter 8

2. 8.1 Built-in Mathematical Function • Visual Basic includes several built-in mathematical functions • Abs • Sqr • Sgn • IsNumeric • Round • Format • Pmt • PV • FV

3. Abs(number) • Returns the absolute value of a number • Form: Abs(number) • Example: Dim intNum As Integer intNum = -5 lblAnswer.Caption = Abs(intNum) ‘ 5 will be displayed

4. Sqr(number) • Returns the square root of a number • You can not take a square root of a negative number • Form: Sqr(number) • Example: Dim intNum As Integer intNum = 9 lblAns.Caption = Sqr(intNum) ‘ 3 will be displayed

5. Sgn(number) • Returns 1,-1,or 0 when the numeric argument is positive, negative or 0 respectively. • Form: Sgn(number) • Example: Dim intNum As Integer intNum = -5 lblAns.Caption = Sgn(intNum) ‘-1 is displayed intNum = 3 lblAns.Caption = Sgn(intNum) ‘1 is displayed

6. 8.2 The IsNumeric Function • Returns True if its argument can be evaluated as a number and False if it cannot. • Form: IsNumeric(argument) • Example: Dim strString As String strString = “123” lblAns.Caption = IsNumeric(strString) ‘True strString = “abc” lblAns.Caption = IsNumeric(strString) ‘False lblAns.Caption = IsNumeric(“2+4”) ‘False lblAns.Caption = IsNumeric(2+4) ‘ True

7. 8.3 The Round Function • Rounds numeric data to specified number of decimal places. • Form: Round(number, decimal places) • Example: Dim dblNum As Double dblNum = 3.4567 lblAns.Caption = Round(dblNum, 2) ‘3.46 will be displayed

8. Format Function • Used to format, or change the appearance of, numeric data. • Form: Format(number, “format type”) • Examples: lblAns.Caption = Format(8789, “General Number”) ‘8789 lblAns.Caption = Format(8789, “Currency”) ‘$8,789.00 lblAns.Caption = Format(8789, “Fixed”) ‘8789.00 lblAns.Caption = Format(8789, “Standard”) ‘8,789.00 lblAns.Caption = Format(89, “Percent”) ‘8900.00% lblAns.Caption = Format(1, “Yes/No”) ‘Yes lblAns.Caption = Format(0, “True/False”) ‘False lblAns.Caption = Format(1, “On/Off”) ‘On

9. 8.5 Built-in Business Function • Three business Built-in function • Pmt(rate, term, principal) • PV(rate, term, payment) • FV(rate, term, investment)

10. Pmt(rate, term, principal) Returns the periodic payment for an installment loan. Rate- is the interest rate per period Term – is the total number of payments to be made Principal – is the amount borrowed Example: Calculate the monthly payments on a 30 – year, $100,000 loan with an annual interest rate of 6%. dblPay = Pmt(0.06/12, 360, -100000) lblAns.Caption = Format(dblPay, “Currency”) ‘$599.55 ***Since payments are monthly, the interest rate must also be computed monthly by dividing the annual rate interest 6% by 12. ***The principal is negative because it is the amount borrowed.

11. PV(rate, term, payment) Returns the present value of an investment. Rate- is the interest rate per period Term – is the total number of payments to be made Payment – amount invested per period Example: Determine the cost of financing a car. $250 per month over a 4 year period is applied to a loan with an interest rate of 8%. dblAmount = 250 * 12 * 4 ‘12000 dblPresent = PV(0.08/12, 48, -250) ‘10240.48 dblFin = dblAmount – dblPresent lblAns.Caption = Format(dblFin, “Currency”) ‘$1,759.52 ***This means that $1,759.52 is spent on Financing

12. FV(rate, term, investment) Returns what a series of equal payments invested at a fixed interest will be worth after a period of time. Rate- is the interest rate per period Term – is the total number of payments to be made Investment – is the amount invested per period Example: You invest $500 per month in a retirement plan earning 8% interest per year. What would it be worth in 20 years. dblFuture = FV(0.08/12, 240, -500) lblAns.Caption = Format(dblFuture, “ Currency”) ‘$294,510.21

13. List Boxes • Allows the user to select a value from a set of values. • Use the Icon to create a List Box Properties of a List Box • Name – use the prefix “lst” for the name • List – stores a group of strings that makes up the list. • Sorted – displays the item in the list in alphabetical order. (Design Time only) • Text – stores the selected list item. (Run Time Only) • ListCount – can be used at run time to determine number of items in the list.

14. List Box • Click Event – is executed when the user clicks on an item in the list box. • AddItem Method – is used to add an item to the list • Example: lstControl.AddItem Item • lstControl – is the name of the list and item is a string object or string double quotes added to the list box • Clear – delete List Box contents of the list. • Example: lstControl.Clear

15. Combo Boxes • Also called collapsible list • The icon is used to create it. • Properties: • Name – use the prefix “cbo” for the name • List – stores a group of strings that makes up the items in the combo box. • Sorted – displays the item in the combo box in alphabetical order. (Design Time only) • Text – stores the selected item in the combo box. (Run Time Only) • ListCount – can be used at run time to determine number of items in the combo box • Style – dropdown combo, simple combo, or dropdown list. Runtime use vbComboDropDown, vbComboSimple, or vbComboDrop-DownList.

16. Combo Boxes • Click Event – is executed when the user clicks on an item in the combo box. • AddItem Method – is used to add an item to the list • Example: cboControl.AddItem Item • cboControl – is the name of the list and item is a string object or string double quotes added to the list • Clear – delete Combo Box contents of the list Example: cboControl.Clear