Derek O'Connor
University College Dublin, Retired
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Is there a better way to randomly generate a Doubly Stochastic Matrix?
@Matt, You are a true blue Matlabber. With just matrix indexing you have written a function which is many times faster than mine...
etwa 13 Jahre vor | 0
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Is there a better way to randomly generate a Doubly Stochastic Matrix?
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...
etwa 13 Jahre vor | 2 Antworten | 0
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AntwortenMemory Utilization of a program in matlab.
A few years ago I suggested to Mathworks that they include memory usage in their Profiler. They said they were thinking about it...
etwa 13 Jahre vor | 0
How to count consuctive 0's inbetween values of 1
This discussion might be useful: <http://www.mathworks.co.uk/matlabcentral/answers/16356-finding-sequences-of-1-s-values>
etwa 13 Jahre vor | 0
Gesendet
The Bellman-Ford-Moore Shortest Path Algorithm
A simple, efficient sparse implementation of the original Bellman-Ford-Moore Shortest Path Algorithm
mehr als 13 Jahre vor | 1 Download |
Poisson random number generator
This is a cleaner fix of |PoissonSamp| % ------------------------------------------------------------- function S = Po...
mehr als 13 Jahre vor | 1
Poisson random number generator
I would like to thank Kang Wook Lee of Berkeley for pointing out an error in the code above. The last line should be |S(i) = k-1...
mehr als 13 Jahre vor | 1
Matlab gives wrong determinant value of 2x2 Matrix without warning.
@Nitin, The "issue" here is not round-off. It is the ill-condition of your matrix. Floating point arithmetic and its rounding...
fast 14 Jahre vor | 1
Matlab gives wrong determinant value of 2x2 Matrix without warning.
The products above are too big to fit in 32-bit integers. You can get the correct result by switching to 64-bit integers: ...
fast 14 Jahre vor | 0
Variation on the travelling salesman problem
@Walter, you're right, I mis-interpreted the problem. So back to the Zero-One LP solution. Given 2 3 1 A = ...
fast 14 Jahre vor | 0
Variation on the travelling salesman problem
It can be solved as a _Zero-One Linear Program_: Let |xij = 1| if the number |aij| is chosen for row |i|, zero otherwise. ...
fast 14 Jahre vor | 0
Inversion of a boolean matrix
*WRONG AGAIN* In testing Walter's suggestion about row and column sums I realized that |isInvBool2| is wrong. Try |B = [true...
fast 14 Jahre vor | 1
| akzeptiert
Inversion of a boolean matrix
I am adding this crude |O(n^2)| invertibility test as a separate answer because my previous answer has become too long. %...
fast 14 Jahre vor | 0
Frage
Why are the BLAS functions in R2011b much faster than R2008a?
Here are the results of a simple Matrix Benchmark test with |n = 10^3; A = rand(n,n)| Dell Precision 690, 2x4-Core Xeon 354...
fast 14 Jahre vor | 1 Antwort | 0
1
AntwortDo you think that MATLAB is expensive?
The academic version of Matlab at about €500 is too expensive for me, a retired lecturer. Cleve Moler in his SIAM oral history i...
fast 14 Jahre vor | 4
Poisson random number generator
I prefer this: % ------------------------------------------------------------- function S = PoissonSamp(lambda,ns); ...
fast 14 Jahre vor | 1
Poisson random number generator
@Ahmed, you're correct, it is not correct. The function below is a Matlab translation of Kroese's algorithm. It seems to wor...
fast 14 Jahre vor | 0
Poisson random number generator
Dirk Kroese has excellent notes here: <http://www.maths.uq.edu.au/~kroese/mccourse.pdf>, which are based on his book: D.P. Kr...
fast 14 Jahre vor | 1
When to use the Secant Method of finding roots?
I would like to qualify what John says: "Methods like the secant method are rarely very good choices anyway." This is arguabl...
fast 14 Jahre vor | 1
randsample issues and generating random numbers from large populations
Here are two functions for taking a sample |S| of size |Ns| from a large, simply-defined population |P| of size |Np|. Both use ...
fast 14 Jahre vor | 1
Random sample without replacement
If you don't have access to *|R2011b|* and |randsample|, then the function below is reasonably fast on my |Dell Precision 690, ...
fast 14 Jahre vor | 1
Solve for x in (A^k)*x=b (sequentially, LU factorization)
Contrary to what Walter says, LU Decomposition is a great help in this problem. See my solution notes to Lab Exercise 6 --- LU...
etwa 14 Jahre vor | 1
speed up finding common values in multiple matrices
Here are some tests on loopy alternatives to vectorized functions. %----------------------------------- function [z,A,...
mehr als 14 Jahre vor | 0
Finding Sequences of 1's values
Jan, I'm using the Add-an-Answer window because the comment window is hard to use for all but short, text-only replies. I post...
mehr als 14 Jahre vor | 0
Finding Sequences of 1's values
This is a more general and simpler solution than my previous answer. %-------------------------------------------------------...
mehr als 14 Jahre vor | 0
Finding Sequences of 1's values
If you don't have any toolboxes then this plain Matlab function may help. It is based loosely on the WordCount procedure in Kern...
mehr als 14 Jahre vor | 1
Inversion of a boolean matrix
*THEOREM*. _If a Boolean matrix B possesses a one-sided inverse, that inverse is also a two-sided inverse. Furthermore suc...
mehr als 14 Jahre vor | 4
[DEPRECATED] What frustrates you about MATLAB?
At Walter Roberson's request I'm reposting this answer here. *Boredom Forecast*: High(78/100). _Discussion of Syntax_. First,...
mehr als 14 Jahre vor | 1
Problem with execution of "nested if" commands.
*Boredom Forecast*: _Discussion of Syntax_. High: (78/100) First, get the preferred indentation by using "smart indent" in the...
mehr als 14 Jahre vor | 0
