Eso Astrophysics Symposia
DOI: 10.1007/10849171_5
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Fast Algorithms and Efficient Statistics: N-Point Correlation Functions

Abstract: We present here a new algorithm for the fast computation of N -point correlation functions in large astronomical data sets. The algorithm is based on kdtrees which are decorated with cached sufficient statistics thus allowing for orders of magnitude speed-ups over the naive non-tree-based implementation of correlation functions. We further discuss the use of controlled approximations within the computation which allows for further acceleration. In summary, our algorithm now makes it possible to compute exact, … Show more

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Cited by 74 publications
(63 citation statements)
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“…Increasing λ makes N cell larger and for too large λ, the method is slow again. Another scheme relies on a double walk in a quad-tree or a oct-tree according to the dimension of the survey (a hierarchical decomposition of space in cubes/squares and subcubes/subsquares, [461]). This approach is potentially powerful, since it scales as O(N 3/2 g ) according to its authors [461].…”
Section: Estimatorsmentioning
confidence: 99%
See 1 more Smart Citation
“…Increasing λ makes N cell larger and for too large λ, the method is slow again. Another scheme relies on a double walk in a quad-tree or a oct-tree according to the dimension of the survey (a hierarchical decomposition of space in cubes/squares and subcubes/subsquares, [461]). This approach is potentially powerful, since it scales as O(N 3/2 g ) according to its authors [461].…”
Section: Estimatorsmentioning
confidence: 99%
“…Another scheme relies on a double walk in a quad-tree or a oct-tree according to the dimension of the survey (a hierarchical decomposition of space in cubes/squares and subcubes/subsquares, [461]). This approach is potentially powerful, since it scales as O(N 3/2 g ) according to its authors [461]. It is also possible to rely on FFT's or fast harmonic transforms at large scales [636], but it requires appropriate treatment of the Fourier coefficients to make sure that the quantity finally measured corresponds to the estimator of interest, e.g.…”
Section: Estimatorsmentioning
confidence: 99%
“…The algorithm for N = 2 is described next; higher orders are exactly analogous, although more tedious to describe. For details see [21] The spatial configuration of the two-point function is characterized by the distance r between the two points: this should lie within a bin, i.e. b 1 < r ≤ b 2 .…”
Section: N -Point Correlation Functionsmentioning
confidence: 99%
“…Point Correlation (PC) is a data mining algorithm that computes the 2-point correlation statistic by traversing a kd-tree to find, for each point in a data set, how many other points are in a given radius [20]. PC is an unguided algorithm.…”
Section: Benchmarksmentioning
confidence: 99%