CS 105
Functions, IF Functions
What is a function?
What is an IF function? A PMT function?
What is a condition?
What is nesting?
CS 105 Spring 2010
#1
Functions
• An Excel command that does a specific task
• Here’s a common function in Excel:
SUM(A2:B5)
• This function’s task: sum all cell values described
within the parentheses (here, the range A2:B5)
– the answer is called the function’s return value
• Why functions? Define once, use many times
– simply change the stuff within parentheses
– called the arguments of the function
CS 105 Spring 2010
#2
Arguments
• A function has a name and arguments
• Arguments can be data, cell names/ranges or
other functions
• Examples:
SQRT (9)
one argument
AVERAGE (A3, A5, A7)
three arguments
SUM (A1:A10, Totals)
two arguments
(a range and the
name of a range)
CS 105 Spring 2010
#3
Built-in functions
• Excel comes pre-loaded with many useful functions
• Categories include:
– Math & Trig e.g., SQRT, ABS, COUNT, COUNTA,…
– Statistical
e.g., AVG
– Financial
e.g. PMT
– Text
e.g. CONCATENATE
• Later, we will see how to write our own functions to
extend Excel’s “toolkit” or “library”
CS 105 Spring 2010
#4
PMT function
• PMT function requires interest
rate/period, number of payments, and
amount of loan
•Establish PMT
–Amount of loan
–Down payment
–Interest rate/12
–Term (in months)
CS 105 Spring 2010
#5
As in…
CS 105 Spring 2010
#6
Note:
• Watch out! Repayment is by default from
the bank’s point of view (returns a
negative number, and we want a positive
number).
• In order to find our payment, we make the
final number negative
CS 105 Spring 2010
#7
Quiz on PMT
• Say the interest on a car is 18% a year. In
calculating the interest PER MONTH you:
A. Pay 18% interest each month
B. Pay 18% divided by 12
C. Pay 18% multiplied by 12
CS 105 Spring 2010
#8
Using Goal Seek
Data Tab in
Excel 2007
• I want to pay only $200 a
month. What car can I
afford?
– Change payment total
by changing one of the
above variables
– The top value must
have a formula in it
– Goal: $200
– Computer calculates
the value of the car
you can afford
CS 105 Spring 2010
#9
IF: adding power to functions
• Suppose we want formula #1 under some conditions,
and a different formula #2 under other conditions
• Example: How does the ABS function work?
• ABS(A5) = A5
if A5 >= 0, but
• ABS(A5) = -A5
if A5 < 0
If
• Visually:
A5 >= 0
True
False
-A5
A5
CS 105 Spring 2010
# 10
The IF function
If
Condition
False
True
Apply formula #1
(after first comma)
Apply formula #2
(after second comma)
CS 105 Spring 2010
# 11
How the IF function works:
eg, single IF statement looks like this:
IF(A2>90, “A”, “B”)
IF (logical test,
value if true,
value if false)
Note: string data in a formula must be surrounded by “ ”, why?
CS 105 Spring 2010
# 12
Commission example
If TEESALES sells $100,000 worth of tee
shirts, the sales commission rate will be 6%. If
the sales total is less than $100,000, the rate
will be only 5%.
Finding the Commission
for sales >= $100,000, pay 6% of sales
for sales < $100000, pay 5% of sales
CS 105 Spring 2010
# 13
Example IF function wizard
An IF function tests for a condition
You can type the IF function directly in the formula
box or use the dialog box of the IF Function
CS 105 Spring 2010
# 14
Example of IF
=IF(B3>=100000, .06*B3, .05* B3)
B3>=100000?
TRUE
.06*B3
FALSE
.05*B3
CS 105 Spring 2010
# 15
Nested
IFs
• If TEESALES sells $100,000 worth of tee
shirts, the sales commission rate will be
6%.
• If the sales total is equal to or more than
$80,000, but less than $100,000, the rate
will be 5%.
• If total sales are below $80,000, the rate
will be 3.5% of sales.
CS 105 Spring 2010
# 16
Example 2 of IF
B3>=100000?
FALSE? Then another test...
TRUE
B3>=80000?
.06*B3
TRUE
FALSE
.035* B3
.05*B3
=IF( B3>=100000, .06*B3, IF(B3>=80000, .05*B3, .035*B3) )
CS 105 Spring 2010
# 17
Practice with Relational Operators
• A1 = B1
• A1 <> B1
-- FALSE
-- TRUE
• A1 = B2
• A1 < B1
-- FALSE
-- TRUE
• A1 < B2
• A1 = A2
-- TRUE
-- TRUE
• A1 >= A2 -- TRUE
• A2 > B2 -- FALSE
CS 105 Spring 2010
# 18
AND, OR, NOT Functions
Formula view
Output of formulas:
CS 105 Spring 2010
# 19
COUNTIF
Function
• Syntax: COUNTIF(Range, Criteria)
• Can be used on a summary worksheet, as in lab
Download employee.xls to practice this
CS 105 Spring 2010
# 20
SUMIF
Function
• The SUMIF function adds figures to a total only if they
match a certain criterion
• The syntax is
SUMIF( range, criteria to check, range where numbers are)
CS 105 Spring 2010
# 21
Text Functions
• Concatenation (putting two words together)
• Concatenation can be done by a function
– e.g. =CONCATENATE(B3,C4)
• Operands can be :
character strings: “Tarzan” & “Jane”
– cell addresses containing text values: B3
–
• Concatenation can also be done by using an operator
&
e.g. = B3 & C4
CS 105 Spring 2009
# 22
Adding a space
• Strings in formulas must always appear in quotes
in Excel.
• To add a space, just put it between quotes.
• Remember, there is an ASCII value for a space!
• You can also put a space between the quote and
the start of Water
CS 105 Spring 2009
# 23
To Summarize
• What is a function?
• What is an IF function? A PMT function?
• What is a condition?
• What is nesting?
CS 105 Spring 2010
# 24