XXt.compute {rpc} | R Documentation |
XXt Computation
Description
For an input matrix X, This function computes UU' = tcrossprod(U) where U = scale(X) in a memory efficient way.
Usage
XXt.compute(
X,
meanX = NULL,
varX = NULL,
ncores = 4,
check = TRUE,
chunksize = 1000
)
Arguments
X |
The input matrix of type ‘matrix’ or ‘dgCMatrix’. No need to center or scale X as that would be done implicitly. |
meanX |
Vector of column means of X. Will be computed if not provided. |
varX |
Vector of column variances of X. Will be computed if not provided. |
ncores |
the number of cores to be used. Default is 1. |
check |
check for zero variances. |
chunksize |
When using openmp parallelization, this would be the chunk size under a dynamic scheduling. |
Value
a nrow(X) x nrow(X) dense symmetric matrix.
Author(s)
Somak Dutta
Maintainer: Somak Dutta <somakd@iastate.edu>
Examples
require("Matrix")
set.seed(123)
x <- rsparsematrix(100,100,density = 0.3)
norm(XXt.compute(x) - tcrossprod(scale(x))) # (4.783951e-13 on my machine)
[Package rpc version 2.0.3 Index]