general computer science for engineers cisc 106 lecture 04 roger craig computer and information...
Post on 20-Dec-2015
216 views
TRANSCRIPT
General Computer General Computer Science Science
for Engineersfor EngineersCISC 106CISC 106
Lecture 04Lecture 04
Roger CraigComputer and Information Sciences
9/11/2009
Lecture ObjectivesLecture ObjectivesIf statements (nested)Logical OperatorsMatlab Output
IF StatementsNested if statements can be used
when two things have to be true for a command to execute
IF StatementsUsing nested if
statements
if (x < 5)
if ( x > 2)
y = 500
else
y = 300
end
else
y= 200
end
IF StatementsUsing nested if
statements
if (x < 5)
if ( x > 2)
y = 500
else
y = 300
end
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
&
&&
A & BA
T F
BT T F
F F F
Logical Operators - OR
|
||
A | BA
T F
BT T T
F T F
Logical Operators - NOT~
~A
T F
F T
Numbers as True/FalseWhat do you think would happen
here:
if (5)
disp(‘5 is a true value’);
else
disp(‘5 is a false value’);
end
Numbers as True/False Group activity: evaluate the
following as true or false for x=5:
1. x < 7 & 3 < x2. ˜(x / 2 > 1 & x < 0)3. x ˜= 5 & x + 2 > 6 | x > 54. x + x == 2 * x && ˜x
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 OutputFormatted OutputExample:
◦ “There are 5 widgets in inventory”◦ fprintf(‘There are %d widgets in inventory’,
widgets);
Matlab OutputFormatted OutputExample:
◦ “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 quotesIf fid is set to one or omitted the output goes
to the screen.
Arrays
ArraysArrays
ArraysArraysFundamental unit of data in MATLABCollection of data into rows and
columns(MATrix LABoratory)1 dimensional, vector2 dimensional, matrix0 dimensional, scalar (a 1x1 array)
Row vector, column vector , transpose
ArraysArrays
Array commandsArray commandsa = [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 continuedArrays continuedzeros(), ones(), eye()scalar vs. array arithmetic
+, - , * (.*) , / (./) ^ etc.