landyszalay {cooltools}

Two-point correlation estimation

Description

Evaluates the Landy-Szalay (1993) estimator of the two-point correlation function of a point set D given a random comparison set R. The two point sets D and R can be made of different numbers of points, as the pair-counts are automatically normalized according to the number of points. In fact, it is often preferable to make the R set larger to reduce the R-related shot noise in the two-point estimator.

Usage

landyszalay(D, R, dr = 0.1, cpp = TRUE)

Arguments

D

n-element vector or n-by-d matrix of d-dimensional positions of the data points

R

m-element vector or m-by-d matrix of d-dimensional positions of the random comparison points

dr

bin size for the evaluation of the two-point correlation function

cpp

logical flag; if set to TRUE (default) a fast implementation in C++ is used to count the point-pairs in distance bins, otherwise the counting is performed less efficiently in R.

Value

Returns a data frame with the two-point statistics of the data points:

r

vector with the mid-points of the distance bins for which the two-point correlation function has been evaluated.

xi

values of the two-point correlation function at the distances r.

err

Poisson errors of xi.

Author(s)

Danail Obreschkow

See Also

paircount