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In this exercise, you will implement linear regression and get to see it work on data. Before starting on this programming exercise, we strongly recom- mend watching the video lectures and completing the review questions for the associated topics.
To get started with the exercise, you will need to download the starter code and unzip its contents to the directory where you wish to complete the exercise. If needed, use the cd command in Octave/MATLAB to change to this directory before starting this exercise.
You can also find instructions for installing Octave/MATLAB in the “En- vironment Setup Instructions” of the course website.
Files included in this exercise
ex1.m - Octave/MATLAB script that steps you through the exercise
ex1 multi.m - Octave/MATLAB script for the later parts of the exercise ex1data1.txt - Dataset for linear regression with one variable ex1data2.txt - Dataset for linear regression with multiple variables submit.m - Submission script that sends your solutions to our servers [?] warmUpExercise.m - Simple example function in Octave/MATLAB [?] plotData.m - Function to display the dataset
[?] computeCost.m - Function to compute the cost of linear regression
[?] gradientDescent.m - Function to run gradient descent
[†] computeCostMulti.m - Cost function for multiple variables
[†] gradientDescentMulti.m - Gradient descent for multiple variables
[†] featureNormalize.m - Function to normalize features
[†] normalEqn.m - Function to compute the normal equations
? indicates files you will need to complete
† indicates optional exercises
Throughout the exercise, you will be using the scripts ex1.m and ex1 multi.m. These scripts set up the dataset for the problems and make calls to functions
that you will write. You do not need to modify either of them. You are only required to modify functions in other files, by following the instructions in this assignment.
For this programming exercise, you are only required to complete the first part of the exercise to implement linear regression with one variable. The second part of the exercise, which is optional, covers linear regression with multiple variables.
Where to get help
The exercises in this course use Octave1 or MATLAB, a high-level program- ming language well-suited for numerical computations. If you do not have Octave or MATLAB installed, please refer to the installation instructions in the “Environment Setup Instructions” of the course website.
At the Octave/MATLAB command line, typing help followed by a func- tion name displays documentation for a built-in function. For example, help plot will bring up help information for plotting. Further documentation for Octave functions can be found at the Octave documentation pages. MAT- LAB documentation can be found at the MATLAB documentation pages.We also strongly encourage using the online Discussions to discuss ex- ercises with other students. However, do not look at any source code written by others or share your source code with others.
1 Simple Octave/MATLAB function
The first part of ex1.m gives you practice with Octave/MATLAB syntax and the homework submission process. In the file warmUpExercise.m, you will find the outline of an Octave/MATLAB function. Modify it to return a 5 x
5 identity matrix by filling in the following code:
A = eye(5);
1 Octave is a free alternative to MATLAB. For the programming exercises, you are free to use either Octave or MATLAB.
When you are finished, run ex1.m (assuming you are in the correct di- rectory, type “ex1” at the Octave/MATLAB prompt) and you should see output similar to the following:
ans =
Diagonal Matrix
1 0 0 0 0
0 1 0 0 0
0 0 1 0 0
0 0 0 1 0
0 0 0 0 1
Now ex1.m will pause until you press any key, and then will run the code for the next part of the assignment. If you wish to quit, typing ctrl-c will stop the program in the middle of its run.
1.1 Submitting Solutions
After completing a part of the exercise, you can submit your solutions for grading by typing submit at the Octave/MATLAB command line. The sub- mission script will prompt you for your login e-mail and submission token and ask you which files you want to submit. You can obtain a submission token from the web page for the assignment.