Community Profile # Ben Petschel

Last seen: 6 mois ago Active since 2009

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How to order values within a cell array more efficiently??
The following should work regardless of the ordering of the two rows: [~,idx] = ismember(ratings(1,:),ratings(2,:)); ord...

presque 8 ans ago | 2

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Approximate vertex cover problem
Assuming you've got an incidence matrix A with A(u,v) if there is an edge from u to v, then a random edge could be selected with...

presque 8 ans ago | 0

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How can I make the negative output values of the linprog optimization to be treated as if they was positive when optimizing a problem?
If you need to minimise something like abs(x), just replace x with y-z so your objective becomes to minimise y+z with y>=0 and z...

presque 8 ans ago | 1

2nd order ODE with variable coefficients
You'll need to rewrite the second-order ODE as a first-order vector ODE. Put y1=y, y2=y1', so y2'=y''. Try ode45, with f = ...

presque 8 ans ago | 0

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Making fmincon display function argument at each iteration
The utility <http://www.mathworks.com/matlabcentral/fileexchange/44120-peek PEEK> on the file exchange can be used to tell you w...

presque 8 ans ago | 0

how plot complementary cumulative density function (CCDF) of data points?
If you have the stats toolbox: ecdf(data,'function','survivor') will plot the CCDF.

presque 8 ans ago | 1

probability of a run of k heads or more in N tosses of a fair coin N>>k
The method in the link you gave can be modified to avoid the need for arbitrary-precision integer arithmetic in calculating the ...

presque 8 ans ago | 0

Genetic Algorithm - Fitness function value differences...
An alternative way to record the evaluated points is with the utility <http://www.mathworks.com/matlabcentral/fileexchange/44120...

presque 8 ans ago | 0

The utility <http://www.mathworks.com.au/matlabcentral/fileexchange/44120-peek PEEK> on the file exchange is useful for this sor...

presque 8 ans ago | 0

Variance in Ornstein Uhlenbeck process
That's an interesting method, though it's not obvious to me how it works and I couldn't see any reference to it in the planet ma...

presque 9 ans ago | 0

Question

calculate tangent of 1e100
How do you calculate trig functions with very large arguments? For example, in "Surely you're joking, Mr Feynman", Richard te...

presque 9 ans ago | 1 answer | 0

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Question

Is the new Cramer's rule algorithm really as good as LU?
The Wikipedia article on Cramer's rule cites a recent paper that claims to have an O(n^3) algorithm: Ken Habgood and Itamar Are...

environ 10 ans ago | 0 answers | 0

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Block diagonalize a matrix
It turns out to be easier than I thought. Given V such that A*V=V*E we find any W such that [W,V] is invertible and if A*W = W*...

plus de 10 ans ago | 0

Question

Block diagonalize a matrix
Given a square matrix A and a rectangular matrix V, how do we find a complement U such that [U,V]\A*[U,V] is block diagonal? Fo...

plus de 10 ans ago | 1 answer | 0