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General Computer Science
for Engineers
CISC 106
Lecture 04
James Atlas
Computer and Information Sciences
6/17/2009
Lecture Overview
If statements
 Logical Operators
 Matlab Output


Data Structures
 Arrays
IF Statements

Review
IF Statements

Nested if statements can be used when
two things have to be true for a
command to execute
IF Statements

Using nested if
statements
if (x < 5)

if ( x > 2)

y = 500

else

y = 300
 else

y= 200
 end

IF Statements

Using nested if
statements
if (x < 5)

if ( x > 2)

y = 500

else

y = 300
 else

y= 200
 end

Using multiple
conditions in one if
statement

if ( x < 5 & x > 2)
y = 500
else
y = 200
end





Logical Operators - AND
&
 &&
Logical Operators - OR
|
 ||
Logical Operators - NOT
~
Matlab Output
◦ How do we see information about what is going on
in our program?
Matlab Output
◦ How do we see information about what is going on
in our program?
◦ disp()
Matlab Output
Formatted Output
 Example:
◦ “There are 5 widgets in inventory”
◦ fprintf(‘There are %d widgets in inventory’,
widgets);

Matlab Output
Formatted Output
 Example:
◦ “There are 5 widgets in inventory”
◦ fprintf(‘There are %d widgets in inventory’,
widgets);
 %d acts as a place holder for widget variable at end
of command and is known as a conversion
character.
 Conversion characters specify the notation of the
output.
 Note the variable widgets as the second argument.

Matlab Output
Lets look at the syntax
◦ count = fprintf(fid, format, A, ...)
◦ count – the number of bytes written
◦ fid – refers to opened file
◦ format – is a format string in between
single quotes
 If fid is set to one or omitted the output goes
to the screen.

What if my program is too
complex?
Matlab Debugging
Break
Data Structures

So far we have only talked about single
points of data
Data Structures

Structured data
◦ Defines how multiple pieces of data
relate to each other
Data Structures

Structured data
◦ Defines how multiple pieces of data
relate to each other

We actually have covered one data
structure already
Arrays
Arrays
Arrays
Fundamental unit of data in MATLAB
 Collection of data into rows and
columns
 (MATrix LABoratory)
 1 dimensional, vector
 2 dimensional, matrix
 0 dimensional, scalar (a 1x1 array)


Row vector, column vector , transpose
Arrays
Array commands
a = [1 2 3 4]
 b = [1; 2; 3; 4]
 c = [1 2; 3] (error)
 d = [1 2; 3 4]
 f = d(1,2)
 g(4,5) = 7

Arrays continued
zeros(), ones(), eye()
 scalar vs. array arithmetic


+, - , * (.*) , / (./) ^ etc.