Introduction to Programming in MATLAB

Introduction to Programming in MATLAB Intro. MATLAB Peer Instruction Lecture Slides by Dr. Cynthia Lee, UCSD is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.Based on a work at www.peerinstruction4cs.org.

LOOPS!

Loops! • Computer programmers are extremely lazy, in that we don’t want to do any more typing than necessary • You’ve already seen that instead of re-typing commands, we can use a script or a function • Not only do we not like re-typing—even copying and pasting lines of code is too much work for us! • Instead of copying and pasting lines of code we want to repeat some number of times, we can use a loop!

for loop Copy-and-paste version for loop version for i = 1:6 myvector(i) = 0 end Of course, you can also do this: myvector(1:6) = zeros(1,6) • myvector(1) = 0 • myvector(2) = 0 • myvector(3) = 0 • myvector(4) = 0 • myvector(5) = 0 • myvector(6) = 0

Software Engineering • Can you think of other reasons (besides laziness) that we might want to use programming constructs like scripts, functions, and loops to avoid re-typing or copying and pasting code? • Here are some suggested reasons: • Less prone to errors in the code • Easier to read the code • Code runs faster • Code is more flexible How many of these are true reasons? • 1 of them (b) 2 of them (c) 3 of them (d) 4 of them

for loop Copy-and-paste version for loop version for i = 1:6 myvector(i) = 0 end Of course, you can also do this: myvector(1:6) = zeros(1,6) • myvector(1) = 0 • myvector(2) = 0 • myvector(3) = 0 • myvecter(4) = 0 • myvector(5) = 0 • myvector(6) = 0

What does this code do? • mystery = 1 • for i = 1:10 mystery = mystery * i end • Computes the sum of the integers from 1 to 8 • Computses the average of the integers from 1 to 10 • Computes the factorial of 10 • Computes the median of the integers from 1 to 10

Introduction to Programming in MATLAB