MCS 177 Lab Fall 2014
Sept. 2, 2014

MCS 177, 9/2/14
Contact Info
• Course Instructor: Louis Yu lyu@gustavus.edu
• Lab Instructors:
• Mike Hvidsten hvidsten@gustavus.edu
• Jeff Engelhardt jengelha@gustavus.edu
• Lab Assistants
11:30: Andrew Haisting ( ahaistin@gustavus.edu
)
2:30: Dustin Luhmann ( dluhmann@gustavus.edu
)
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MCS 177, 9/2/14
Today’s schedule
• Course/Lab Details
• Python and Idle
• Python Intro (Sec 1.1-1.5 in textbook)
• Tasks 1 and 2 of Project 1 (if time)
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MCS 177, 9/2/14
Course/Lab
• Course Website : www.gac.edu/~lyu/teaching/mcs177-f14/
• Lectures – Monday, Wednesday, Friday
• Read Assigned sections before class (see class schedule)
• Lab Work – Tuesday, Thursday
• Projects are linked from course site
• This week – Intro (nothing to hand in)
• Submit code via Moodle
• Lab notes/slides at www.gac.edu/~hvidsten/courses/MC177
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MCS 177, 9/2/14
Python – Course Programming Language
• Python is an open source scripting language.
• Developed by Guido van Rossum in the early 1990s
• Named after Monty Python
• Available on MCS computers
• Available for download from http://www.python.org
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MCS 177, 9/2/14
Why Python?
• Simple Syntax – we can focus on solving problems, learning concepts, not coding syntax
• Object-Oriented – all values are essentially objects
• Widely used (Google spider and search engine)
• Powerful String and Math libraries
• Dynamic Typing: Variables do not need to have predefined types
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MCS 177, 9/2/14
Idle GUI Environment:
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MCS 177, 9/2/14
Let’s Get Started!
• Log on to your computer (user name = email name)
• Start Idle
• Try some basic arithmetic examples
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MCS 177, 9/2/14
Arithmetic Operations
Operator
/
*
-
+
//
%
** abs()
Operation
Addition
Subtraction
Multiplication
Float division
Integer division
Remainder
Exponentiation
Absolute value
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MCS 177, 9/2/14
Numerical Data Types
• Integer (int) vs Floating Point (float)
• How can we tell which is which?
A numeric value without a decimal point produces an int value
A numerical value that has a decimal point is represented by a float (even if the fractional part is 0)
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MCS 177, 9/2/14
Numerical Operations
Operations on ints produce ints (except for /)
Operations on floats produce floats,
Mixed operations are converted to floats
>>> 3.0+4.0
7.0
>>> 3+4
7
>>> 3.0*4
12.0
>>> 3*4
12
>>> 10.0/3.0
3.3333333333333335
>>> 10/3
3.3333333333333335
>>> 10 // 3
3
>>> 10.0 // 3.0
3.0
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MCS 177, 9/2/14
Variable Assignment (Section 1.5)
• As in mathematics, much of the power of computer programs is in the use of variables
• Python variables are identified by name
• Must start with a letter
• Ex: x=2, a_1 = x+3
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MCS 177, 9/2/14
Example
• We want to calculate the volume of a cylinder
• volume = area of base * height
• Variables?
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MCS 177, 9/2/14
Example
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MCS 177, 9/2/14
Diagram for Simple Assignment in Python
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MCS 177, 9/2/14
Changing Radius value has no effect on cylinderVolume!
Why not?
10.0
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MCS 177, 9/2/14
How do we make change?
• Need to re-evaluate baseArea and cylinderVolume
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MCS 177, 9/2/14
If time, Start working on Tasks 1 and 2 of Project 1
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