Computer Science 1000
Spreadsheets II
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Spreadsheet Computing
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spreadsheets can be used exclusively for data
formatting and layout
however, their most common application is to
process data
what does this mean?
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in the context of spreadsheets, it means that the
spreadsheet provides new information based on what we
supply
this information can be in the form of data, but also in
formatting (e.g. display negative numbers in red)
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Formula
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a statement in a cell that performs a computation
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every formula has a value
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e.g. math equation, table lookup, etc …
the result of the computation
this is the value that is displayed
the formula itself will be displayed in the formula bar
formulas can be combined
indicated by an initial = sign
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in other words, when the data in a cell begins with =, Excel
interprets the remainder to be a formula
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Formulas - Constant
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constant: a formula whose value is itself
examples include:
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numbers
text
dates
by themselves, constants are not typically
expressed as a formula
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they are usually used in other formulas
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Numeric Constant
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a number
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Numeric Constants
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by themselves, numeric constants aren’t that useful
as formulas
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they have the same functionality outside of formula
instead, they are usually used as part of another
formula
these include:
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numeric operators
function inputs
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Numeric Operators
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Excel accepts the standard math operators
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+, -, * (times), / (divide), ^ exponent
these operators are used in typical binary format
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e.g. to compute 3+4, enter the formula =3+4
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Numeric Operators
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Question: what happens if I omit the equal sign?
Excel interprets the
formula as text, as it
cannot be interpreted
directly as a number or
a date (due to the + in
the middle).
Remember to use =
when using formulae.
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Numeric Operators
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Question: what happens when I combine
operators?
Excel honours the
order of operations that
you are used to:
highest: ^
next: * /
lowest: + -
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Numeric Operators
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Question: suppose I want to perform operations out of order
(e.g. perform the add before the multiply)?
Use parentheses to
reorder your
operations. Operations
in parentheses have
the highest priority.
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Numeric Operators
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Example: compute the average of 1,2,3 and 4.
Use parentheses to
perform the addition
before the division.
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Numeric Operators
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Example 2: Recall our transaction spreadsheet. We used all
numeric constants. Use formulas to compute the final three
amounts:
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Text Constants
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text can also be used as a constant in a formula
however, not as simple as putting the text after the
= sign
Whenever you see a
computed value that
starts with #, it often
indicates an error.
In this case, Excel does
not know that Kev is
meant to be text
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Text Constants
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when text constants are used in a formula, enclose
them in double quotes
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Text Concatenation
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like numeric constants, not often used by
themselves
can be used in concatenation – combine multiple
text elements into a single version
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use the operator &
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Text Concatenation
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when using concatenation, you must specify all of
the characters you want to appear
a common mistake is to forget about spaces
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Mixing Types
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what happens when we do the following?
Excel will attempt to
convert the values
based on the operator
type. In this example,
because & accepts two
text items, it converts
1000 to “1000”
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Mixing Types
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what happens when we do the following?
In this example,
because + accepts two
numbers, it converts “4”
to 4
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Mixing Types
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what happens when we do the following?
In this example,
because - accepts two
numbers, it tries to
convert “CS ” to a
number. Since this
fails, an error is
generated.
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Mixing Types - Precedence
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question: what’s the output of the following?
The & operator has
lower precedence than
all of the math
operators. Hence, the
formula is parsed as:
“1” & ( “2” – 4 )
 “1” & -2
 “1” & “-2”
 “1-2”
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Functions
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a preset formula in Excel
each function has a name
functions accept a set of zero or more inputs
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surrounded by parentheses
separated by commas
a function has a value
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usually, the function performs some computation, and its
value is the result of that computation
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Function - First Example
suppose you want to know the square root
of a number
 Excel has a function called sqrt
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accepts one input – a value or formula
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Function - Inputs
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note that the input to a function can be another
formula, if you like
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the inside formula is evaluated before its value is sent to
the function
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Function - Inputs
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the input to a function can even be another function
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the inside function is evaluated first
its value is sent as the input to the outside function
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Function - Inputs
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your function will expect a particular type as its
input
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will convert if necessary
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Function - Inputs
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your function will expect a particular type as its
input
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an error occurs if it can’t convert
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Functions – No Input
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some functions have no inputs
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the parentheses are still required, to indicate that it’s a
function
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they always return the same value
nothing is placed inside
e.g. pi() - returns the value π
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Functions – Example
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compute the volume of a cylinder of radius 10.4 and height
25.6
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Formula: V = πr2h
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Functions – Example
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spot the error in the formula
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pi is a function, and hence must have parentheses to indicate this
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Functions – Multiple Inputs
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some functions accept more than one input
each input should be separated by commas
example: max
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returns the maximum value amongst all of its inputs
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Functions – Multiple Inputs
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not all inputs need to have the same type
e.g. left
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left accepts a text input S, and a number X, and returns the first X characters in S
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Boolean Values
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a type that can be one of the two following values:
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TRUE
FALSE
think of it like yes (TRUE) or no (FALSE)
these values can be on their own, or in a formula
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Boolean Values
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some function inputs require boolean values
e.g. vlookup (from your lab)
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the last parameter indicates whether the value you are
looking can be an approximate match
approximate: TRUE
exact: FALSE
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Boolean Values
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instead of specifying Boolean values, they are often
computed
this is done using comparison operators
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= (equal)
<> (not equal)
< (less than)
> (greater than)
<= (less than or equal to)
>= (greater than or equal to)
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Comparison Operators
can be used on text types
 can be used on mixed types
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If Statement
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one of the most useful functions in Excel
takes three inputs
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a Boolean value
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a “True” value
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the value of the function if the first input is true
a “False” value
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remember: can be a formula that returns a Boolean
the value of the function if the first input is false
in other words, it selects either the second or third input as its
value, depending on whether its first input is true or false
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If Statement
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remember: any of the inputs can be formula themselves
Since 3 < 4 is true, the
value of this formula is
the second input, or
sqrt(16)
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If Statement
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remember: any of the inputs can be formula themselves
Since 3 > 4 is true, the
value of this formula is
the third input, or
max(6,7)
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Excel Functions
there are many functions built into Excel
 Math
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abs – returns the absolute value of its input
 sin, cos, tan – returns the sine/cosine/tan value
of its input
 average – returns the average value of its input
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Excel Functions
there are many functions built into Excel
 Text
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len – returns the number of characters in its
input string
 lower – converts all characters in its input to
lower case
 upper – converts all characters in its input to
upper case
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Excel Functions – Help
Excel has a handy feature that assists users
in function recall
 clicking on the formula bar label will activate
a dialog that lists all of the functions
available in Excel
 this includes a categorization, and a search
feature
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Excel Functions – Help
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furthermore, selecting a function from this
list shows a dialog with a place to insert
each input, with a description of what it does