Community Profile

Professional Interests: Algorithms and Data Structures, Numerical Analysis

Contact

Top 1% contributor

49 downloads

2 years ago

The academic version of Matlab at about €500 is too expensive for me, a retired lecturer. Cleve Moler in his SIAM oral history i...

3

Answered 3 years ago

*THEOREM*. _If a Boolean matrix B possesses a one-sided inverse, that inverse is also a two-sided inverse. Furthermore suc...

Reply from Derek O'Connor: I must apologize for the omission of the RNG used. It was in my original draft but somehow got left ...

accepted

1

Answered 4 years ago

The Birthday Paradox or problem asks for the probability that in a room of n people, 2 or more have the same birthday (not date)...

5 Answers

2

Asked 4 years ago

Jorge " <sergio_l_nospam@hotmail.com> wrote in message 64 bit Matlab R2007b does not have a compiler. Here is what I got from M...

39583 views

Responded 7 years ago

The simplest tree data structure is an array of parent 'pointers' A tree with n nodes can be stored using two arrays : Node(1:n...

33271 views

Responded 5 years ago

An answer should _illuminate_ not _dazzle_.

Two small tweaks: Change p(1:m) = U+1 to p = zeros(1,m); Change while member(r,p,k) to while member(r,p,k-1) Derek O'C...

21404 views

Responded 4 years ago

Roger, Bruno, My apologies. I had forgotten that you were using a descending for-loop. This is what Durstenfeld (1964) used, an...

Bruno, Point (2) is a point. for k = 2:m does not work. Note the first statement in the for k-loop: r = ceil(rand*k); For ex...

snip --- This is a minor variation on Durstenfeld's implementation of the Fisher-Yates Shuffle, referred to by Jan Simon above,...

Steve, Would you please enumerate the *limitations* of 64-bit integer operations vis a vis double precision operations. For ex...

19556 views

Sorry for the mess. The period at the end of the url is the problem. It should be http://www.mathworks.com/matlabcentral/fileex...

16930 views

Responded 6 years ago

Visual C++ 2008 Express works with Matlab 2007a (64bit) and above. All the information you need is here : http://www.mathwork...

@Nitin, The "issue" here is not round-off. It is the ill-condition of your matrix. Floating point arithmetic and its rounding...

I would like to qualify what John says: "Methods like the secant method are rarely very good choices anyway." This is arguabl...

Here are two functions for taking a sample |S| of size |Ns| from a large, simply-defined population |P| of size |Np|. Both use ...

If you don't have access to *|R2011b|* and |randsample|, then the function below is reasonably fast on my |Dell Precision 690, ...

If you don't have any toolboxes then this plain Matlab function may help. It is based loosely on the WordCount procedure in Kern...

Berk, Graph layout is a very difficult problem and has been studied for many years. AT&T has a department or section dedica...

Roger, I think your method is a modification of the Fisher-Yates shuffle algorithm as implemented by Durstenfeld, CACM 1964. It...

12179 views

Responded 3 years ago

See this thread: http://www.mathworks.com/matlabcentral/newsreader/view_thread/304272#824982 Derek O'Connor

Here is a profile of the call |n = 2*10^3; M = DStochMat02(n,ones(n)./n);| More specifically, can the hot-spot, statement 1...

2 Answers

0

Asked 2 years ago

Abstractly, a random permutation generator (RPG) is a function that maps a random bit-string of length |b| into a permutation of...

4 Answers

Asked 3 years ago

John D'Errico" <woodchips@rochester.rr.com> wrote in message <gptlc9$ra8 John, Your VP toolbox is a great addition to Matlab. ...

10876 views

Sean, The notes here http://www.derekroconnor.net/NA/LE/LE-2006-2.pdf explain why your code gives the wrong answers. I hope y...

10682 views

Dear James, I'll look at your mex functions later but respond to the first part of your post here. You say : So that double...

8570 views

Dear Romero, Are you familiar with Shakespeare's phrase in Henry IV, Part 2, "Don't shoot the messenger"? --- Anyway, on to you...

Load more