Comments for Doug's MATLAB Video Tutorials

Comment on Basics: Volume visualization: 3/9 Display of scatter3 and slice plots by Vick

Vick — Sat, 07 Nov 2009 17:12:04 +0000

Hey Doug, sure enough a good topic. Is it possible to put all the codes together (starting from your video1/9), so one can play with the parameters and get more insights. My research requires 3D-vector field visualization (Medical Imaging) - Upon completion of all 9 videos, I’m happy to share how I currently do the visualizations and pick the matlab brains on improvements ;)

Comment on Puzzler: Ultimate Frisbee- call it! Wrap up by Arman Boyaci

Arman Boyaci — Tue, 03 Nov 2009 18:06:37 +0000

In order to make a “fair” game, I suggest the following procedure:

Player 1 does not choose Heads or Tails but {HT} or {TH}. Remaining one (HT / TH) is for Player 2.

Assuming that observations are independent, we have the following probabilities:
P{HT} = p(1-p)
P(HH) = p^2
P(TT) = (1-p)^2
P(TH) = (1-p)p

In other words, first we flip twice if we get {HT} or {TH} then we have a winner; otherwise we flip (twice) again.

Comment on Puzzler: Ultimate Frisbee- call it! Wrap up by dhull

dhull — Tue, 03 Nov 2009 15:25:54 +0000

I sent this to my Ultimate Team, I got this link back:

http://www.codingthewheel.com/archives/the-coin-flip-a-fundamentally-unfair-proposition

May or may not be relevant. I suspect it is relevant because the disk is weighted.

-Doug

Comment on Basics: Volume visualization: 2/9 Examples of scalar and vector fields by dhull

dhull — Mon, 02 Nov 2009 18:13:08 +0000

@ JohnA

The people have spoken!

I will bump up the pace. I have the results of the Ultimate puzzler and Episode three for this week, then I will move to a MWF pace until it is over.

Thanks,
Doug

Comment on Basics: Volume visualization: 2/9 Examples of scalar and vector fields by JohnA

JohnA — Mon, 02 Nov 2009 17:37:51 +0000

Doug, definitely interested in a quicker pace if its no problem…anxious to get to some coding (-;

Comment on Reshape a matrix without using a for loop by dhull

dhull — Mon, 02 Nov 2009 16:24:00 +0000

@"Crazee" When I am faced with a problem like this, I make a simple test case and see what happens. Look at this:

a = [1 2; 3 4]
A(:,:,1) = a
A(:,:,2) = a+4
A(:,:,:,2) = A + 10
reshape(A,[2,8])

a =

     1     2
     3     4


A =

     1     2
     3     4


A(:,:,1) =

     1     2
     3     4


A(:,:,2) =

     5     6
     7     8


A(:,:,1,1) =

     1     2
     3     4


A(:,:,2,1) =

     5     6
     7     8


A(:,:,1,2) =

    11    12
    13    14


A(:,:,2,2) =

    15    16
    17    18


ans =

     1     2     5     6    11    12    15    16
     3     4     7     8    13    14    17    18

Comment on Basics: Implementing a formula in MATLAB by dhull

dhull — Mon, 02 Nov 2009 16:10:41 +0000

@Ismael,

You can use the TeX and LaTeX parts of MATLAB for some formulas. For the one above, that was just a screenshot of an e-mail the user sent me.

Doug

Comment on Advanced MATLAB: Capture mouse movement by Fatih

Fatih — Mon, 02 Nov 2009 06:49:57 +0000

@Doug,

I forgot to write here but i find a solution to handle it.

http://img682.imageshack.us/i/adszkh.jpg/

If someone need this i can send my program.

Fatih

Comment on Advanced MATLAB: Capture mouse movement by dhull

dhull — Fri, 30 Oct 2009 18:08:19 +0000

@Fatih,

Good problem. You will just have to make sure that when you set the XData on the original line, you also set it on all the additional lines. You would want to put the callbacks on all the lines so that any of them can move.

Doug

Comment on Integrating to find the volume underneath a set of nonuniformly spaced data by dhull

dhull — Fri, 30 Oct 2009 15:51:04 +0000

@cari,

To integrate the area under your set of Z points, you must make some kind of assumptions as to what happens between X,Y points that you know since there is no volume under a point!

Fitting a surface to the data does that.

Depending on your data, you could simply do a nearest neighbor interpolation, or a linear interpolation. What is the nature of your Z data, and what is the spacing of the X and Y?

-Doug