Questions tagged [sorting]
Sorting is the process of arranging similar items according to a predefined order.
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Computing a sorting matrix for an upper triangular matrix
Assume I have a real upper triangular matrix $U$, there exists an orthogonal matrix $M$ such that $U' = M^T U M$ is also upper triangular and has the same eigenvalues as $U$ but sorted by value.
Is ...
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How to stack N boxes of varying heights into M stacks, most evenly
The "standard" box-stacking algorithm(s) AFAIK assume a single stack and try to put the "largest" boxes on the bottom. The case I want to solve is simply to distribute the N boxes ...
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Resampling an array of objects
Context
I have an array of objects (or a list of dictionaries), sorted in order based on a property of each object, say, time. In JSON, it would look something ...
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Two-dimensional ordering issue – alternate sort order ascending/descending to reduce fluctuations - trivial?
I have a solution in search of a problem that some of you could perhaps help me with.
Let $L$ be a list of elements. Each element has two inherent properties/attributes ($a$, $b$) that can each be ...
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Sorting Triangle vertices based on indices for alpha blending (back to front) C++, OpenGL
I have implemented in OpenGL alpha blending for a triangle mesh. I render this mesh using a vector of indices that indicate which vertex from a vertices vector should be drawn. The problem is to ...
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A robust algorithm to sort a non-convex polygon vertices
Let v_{0},...,v_{N-1} be N points in a Cartesian xy plane defining the vertices of closed polygon (i.e. v_{N} = v_{0}).
Let P_{0}...
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Maintain sorted ring buffer [closed]
I would like to insert elements into a ring (circular) buffer one at a time and maintain a permutation array which keeps track of the sorted elements in ascending order. To do this, I have adapted the ...
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LAPACK zlapmt_ freezes code [closed]
I'm using LAPACK's zggev_ routine to solve some generalized eigenvalue problem.
While it produces the correct results, I want the eigenvalues and according eigenvectors sorted by absolute value.
For ...
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An algorithm to turn descending order into ascending order, but why correct? [closed]
I wonder why does this algorithm below work well? Many appreciates!
Task:
Suppose all elements in an array with length $n = 2^m$ are in descending order: $a_1 > a_2 > ... > a_n$, we need to ...
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extract exhaustive mutually exclusive intervals from larger set of intervals [closed]
I have a collection of time intervals with integer valued endpoints , e.g. (1,2), (2, 6) (5,6), and the number of events falling in each time interval, and I would like to determine if from them I ...
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Fastest multithreaded radix sort
What is the fastest multithreaded radix sort code out there? I am using radix sort to sort the Morton/Hilbert keys when constructing a tree structure. The number of identical keys is in the range of ...
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Sorting eigenvalues by the dominant contribution
[Edited to simplify the question]
I am trying to associate the eigenvalues $E$ of a matrix $H$ to the original rows of the matrix.
Moreover, it would be trivial to sort the eigenvalues in ascending ...
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Is it possible to compute quantiles of a set of numbers, without first sorting those numbers?
I apologize in advances if this is the wrong place to be asking this question, (I had considered putting it on CV first).
I am studying financial (S&P, Dow Jones, etc) data, and would like to ...
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Quicksort - difference in time
I'm testing Quicksort based on Niklaus Wirth algorithm. I'm checking how much time I need to sort an array. There is interesting thing that for an array consisting elements in these sequence:
1 3 ...
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