Doug's MATLAB Video Tutorials

MATLAB training through Cody

Doug — Wed, 02 May 2012 13:05:09 +0000

Cody is one of my favorite ways of learning MATLAB. I have recently created a problem in Cody where you are to solve addition problems of this puzzle style:

    W A I T
  +   A L L
  ---------
  G I F T S
equals:

    9 6 0 8
  +   6 7 7
  ---------
  1 0 2 8 5

What I like about this problem is that it can be broken down into a series of smaller problems. I have made Cody problems for those more fundamental skills also. If you can accomplish the sub problems listed, then they can be combined to solve the original larger problem. If these are popular, I hope to make a large series of problems that can be used to learn and practice the fundamental skills of MATLAB programming.

Choosing a visualization in MATLAB

Doug — Thu, 26 Apr 2012 13:00:45 +0000

Knowing what visualizations of your data are useful is half the challenge. We recently added a plot type gallery to our website. It allows you to see many different MATLAB graphics at once. Find the one that looks like what you want and see a short example of how to do it.

I had collaborated with Flowing Data a while back to add to their flowchart on how to decide which visualization to use. Try them both!

Using convolution to smooth data with a moving average in MATLAB

Doug — Tue, 17 Apr 2012 17:59:38 +0000

I teach the introduction to MATLAB classes for all new hires in the Technical Support group at MathWorks. One of the attendees wanted to know how to do a moving average in MATLAB. This can be useful for filtering, or smoothing, noisy data. I realized I had never covered that on the blog, so here we go! I show how to do this from scratch using conv. If you have the Curve Fitting Toolbox, you might want to check out smooth, which adds some fancier smoothing methods.

Cody problems and programming contest preview?

Doug — Tue, 03 Apr 2012 18:30:52 +0000

The MATLAB programming contest team has released six Cody problems today. These should be interesting in their own right, but those of you that want a head start on the programming contest that starts tomorrow might want to look at them too. They are ‘thematically similar’ to this season’s programming contest. They could help you start thinking in the right direction for the contest that starts at Noon on Wednesday.

Enjoy!

MATLAB Tutorial, processing an Excel file in MATLAB

Doug — Wed, 28 Mar 2012 17:08:43 +0000

It is very commong to read through all the values in an Excel spreadsheet to process them in MATLAB. Here is a simple example of importing Excel in MATLAB and looping through the values.

Regression in MATLAB

Doug — Fri, 16 Mar 2012 15:21:53 +0000

There are three new functions for regression in the 2012a release of MATLAB. I am not an expert in this area, but Richard is. Enjoy his video about these capabilities.

MATLAB 2012a: Face detection

Doug — Fri, 09 Mar 2012 18:49:54 +0000

The new release of MATLAB is here!

I was looking through it, and one thing that caught my eye the most was some face detection algorithms have been added. This is great because I get questions about it a fair amount. I am lending the blog to my friend and colleague, Bruce, to show you what is new in this area of MATLAB.

ps. I just watched this video with someone in the office. His response: “I spent one and a half years of grad school trying to do that!”

Piecewise linear curve fitting

Doug — Fri, 02 Mar 2012 17:37:02 +0000

This week, I am getting back to my blogging roots and I want to highlight (and thank) John D’errico for a great file Exchange submission. That file is Shape Language Modeling.

Recently I had some very noisy data that I wanted to fit a curve to. The problem is there were different regions that were somewhat linear, but the overall data was far from linear. A spline or a polynomial did not capture the behavior in a global sense. What I wanted was the ability to fit a line to each region. SLM does that right out of the box.

I think it is very instructive to look at how this code was packaged up. There is a clearly labeled tutorial that was easy to scan looking for an example like what I wanted to do. All of the files have lots of comments. sometimes more comments that code I think. The files are named coherently so they make a nice package. These are all great things to make a package that other people can use.

Cody challenges added: Poker Series

Doug — Thu, 23 Feb 2012 21:04:31 +0000

Cody is a great way to learn MATLAB. Recently, a new series of problems have been added. This series of problems will be excellent for people that are new to MATLAB to solve. There are 11 problems, that taken together will walk you down a path such that at the end, you will have some code that can compare two sets of playing cards and determine which can make the better poker hand.

The math behind this will give you a chance to practice lots of indexing, comparisons, pattern matching, flow control, cell arrays, structures, sub-functions, etc. The test suites have been designed to catch as many edge cases as possible so that to successfully finish each function, you will need to really get it right. You then will get a chance to reuse the code from each challenge to the next.

You will also be able to see how other people solve these problems. For instance, I have put my solution in there to be viewed. My code is usually very long, but easy to understand. You will also see other people using more advanced techniques that use less lines of code. This gives you a chance to see code of known functionality that uses (possibly) unfamiliar techniques.

I recommend you start with the code IsStraightFlush.

Can you make code that can tell that this matrix:

[0 0 0 0 0 0 0 0 0 0 0 0 0;
 0 0 1 1 1 1 1 0 0 0 0 0 0;
 0 0 0 0 0 0 0 0 0 0 0 0 0;
 0 0 0 0 0 0 0 0 0 0 0 0 0];

contains five cards in the same row and adjacent columns, while

[0 0 0 0 0 0 0 0 0 0 0 0 0;
 0 0 1 1 1 0 1 0 0 0 0 0 0;
 0 0 0 0 0 0 0 0 0 0 0 0 0;
 0 0 0 0 0 0 0 0 0 0 0 1 0];

does not? What about the tricky case where the Ace (column 1) is considered high?

[0 0 0 0 0 0 0 0 0 0 0 0 0;
 0 0 0 0 0 0 0 0 0 0 0 0 0;
 1 0 0 0 0 0 0 0 0 1 1 1 1;
 0 0 0 0 0 0 0 0 0 0 0 0 0];

Highlighting solutions to Project Euler problems 001-005

Doug — Tue, 14 Feb 2012 17:29:39 +0000

I’ve been excited by the great response to the Project Euler problems that I’ve posted on Cody. This video takes a look at my favorite submission for each of the first five problems. Take a look at how other people have solved these problems, you might see some MATLAB techniques that are new to you.