Doug’s MATLAB Video TutorialsNovember 20th, 2009Basics: Volume visualization: 6/9 Displays quiver3 and coneplotThis short video is the sixth of a series of nine that talks about volume visualization. Patrick gave this talk internally to help technical support engineers understand capabilities of MATLAB for volume visualization.
I like his slow, clear, methodical presentation with great visualizations. It is the first time I have deeply understood some of the volume visualization techniques we have.
November 17th, 2009Basics: Volume visualization: 5/9 Making a 3-d plot ‘pretty’ with lighting, shading, interpolation, etc…This short video is the fifth of a series of nine that talks about volume visualization. Patrick gave this talk internally to help technical support engineers understand capabilities of MATLAB for volume visualization.
I like his slow, clear, methodical presentation with great visualizations. It is the first time I have deeply understood some of the volume visualization techniques we have.
November 13th, 2009Contest: Flood wrap-upHere is the wrap up of the MATLAB programming contest that we just ran.
However, we can see that on some of the boards, the winning entry did significantly better. The boards that it won on were those with the large valued 80’s randomly around the board.
Surprising to me, the 1000 node solver did noticably better on a couple of the tall skinny boards like this:
That leaves me wondering if someone could have done a quick check to see if the board had 30 colors or so, and then tried the simpler solver. It looks like this would have made some significant gains… A good contest, congratulations to all that participated. November 11th, 2009Basics: Volume visualization: 4/9 Display of contourslice and isosurfaceThis short video is the fourth of a series of nine that talks about volume visualization. Patrick gave this talk internally to help technical support engineers understand capabilities of MATLAB for volume visualization.
I like his slow, clear, methodical presentation with great visualizations. It is the first time I have deeply understood some of the volume visualization techniques we have.
November 6th, 2009Basics: Volume visualization: 3/9 Display of scatter3 and slice plotsThis short video is the third of a series of nine that talks about volume visualization. Patrick gave this talk internally to help technical support engineers understand capabilities of MATLAB for volume visualization.
I like his slow, clear, methodical presentation with great visualizations. It is the first time I have deeply understood some of the volume visualization techniques we have.
November 4th, 2009Contest: FloodingThe 20th MATLAB programming contest just went live!
Our more faithful blog readers might have a head start on this puzzle… Finding four connected regions. A puzzler about the game that inspired this contest. Winning entries to the above puzzler. November 3rd, 2009Puzzler: Ultimate Frisbee- call it! Wrap upI do not know why I am still always amazed at the many different ways that simple problems are solved by different people. To end the suspense for everyone playing along at home,“For two coins (i.e. Frisbees®) that have the same probability of being heads or tails (but not necessarily fair coins) you are at worst going to win 50% of the time when you choose ’same’.” (Here is the original post) My argument on the Ultimate Frisbee field was “Imagine the two Frisbee come up heads 99% of the time, what do you choose?” “Same!” “What about 98%?” “Same” “This logic holds all the way through, even to 50.00001. At 50% it just does not matter, so always choose same.”
The more rigorous and MATLAB proofs were more along these lines:
This was a GUI that you watched as it went through a Monte Carlo simulation. Thanks Richard Arman did a more traditional proof, citing Wikipedia
Let p be the probability of having tails. The probability of having "different" is p(1-p)+(1-p)p. The probability of having "same" is p^2+(1-p)^2. From the arithmetic mean geometric mean inequality, we know that p^2+(1-p)^2 >= 2*p(1-p) and equality holds if p=1-p which means p=1/2. Therefore “same” is better choice for any p value.
There were many variations on this plot:
I liked Zane’s here because it shows how much better off you are with ’same’ for each value of unfairness in the coin.
Christopher won the challenge by going to the next level, pointing out that you could make these unfair Frisbees almost fair by flipping three and calling for an odd number (1 or 3) vs even number (0 or 2) of heads.
Thank you everyone for playing, and finally putting this question to rest! Now the ethical question, knowing the coin flip is unfair, is it in the Spirit of The Game to let the other guy choose? Should we move to Christopher’s method of flipping three Frisbees? Frisbee® is a Registered Trademark of © 2004 Wham-o Inc. All Rights Reserved. October 30th, 2009Basics: Volume visualization: 2/9 Examples of scalar and vector fieldsThis short video is the second of a series of nine that talks about volume visualization. Patrick gave this talk internally to help technical support engineers understand capabilities of MATLAB for volume visualization.
I like his slow, clear, methodical presentation with great visualizations. It is the first time I have deeply understood some of the volume visualization techniques we have.
October 27th, 2009Puzzler: Ultimate Frisbee- call it!I play a fair amount of Ultimate Frisbee® between lunch across the street at Cognex and playing with Boston Ultimate Disk Alliance. Games of Ultimate start with the two teams flipping two Frisbees in the air and calling “Same or different” My team was trying to figure out which is the most likely outcome.I made a convincing argument, but I am curious what kind of persuasive MATLAB-based ‘proofs’ can be made. I am offering a MATLAB t-shirt to the most persuasive entry. Use published MATLAB files, GUI’s, MATLAB script or function, whatever you think will be most convincing. Contest ends this time next week.
Assumptions: The Frisbees (or coins) are either ‘heads’ or ‘tails’. The coins may or may not be ‘fair’ (i.e. they might be heads 80% of the time!), however the odds of heads versus tails for the two coins is the same for both coins. Send entries to hull@MathWorks.com (no .rar files please!) (Here is the result of this now closed contest) Frisbee® is a Registered Trademark of © 2004 Wham-o Inc. All Rights Reserved. October 23rd, 2009Basics: Volume visualization: 1/9 Defining scalar and vector fieldsThis short video is the first of a series of nine that talks about volume visualization. Patrick gave this talk internally to help technical support engineers understand capabilities of MATLAB for volume visualization.I like his slow, clear, methodical presentation with great visualizations. It is the first time I have deeply understood some of the volume visualization techniques we have. Sorry, Dr. H, but I really did not understand Div, Grad, Curl and all of that until Patrick explained it later in this series! 1 of 9 Definitions for scalar and vector fields.
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