MatCreateCentering#
Creates a new matrix object that implements the (symmetric and idempotent) centering matrix, I - (1/N) * ones*ones’
Synopsis#
#include "petscmat.h"
PetscErrorCode MatCreateCentering(MPI_Comm comm, PetscInt n, PetscInt N, Mat *C)
Collective
Input Parameters#
comm - MPI communicator
n - number of local rows (or
PETSC_DECIDE
to have calculated if N is given) This value should be the same as the local size used in creating the y vector for the matrix-vector product y = Ax.N - number of global rows (or
PETSC_DETERMINE
to have calculated if n is given)
Output Parameter#
C - the matrix
Notes#
The entries of the matrix C are not explicitly stored. Instead, the new matrix object is a shell that simply performs the action of the centering matrix, i.e., multiplying Cx subtracts the mean of the vector x from each of its elements. This is useful for preserving sparsity when mean-centering the columns of a matrix is required. For instance, to perform principal components analysis with a matrix A, the composite matrix CA can be passed to a partial SVD solver.
See Also#
Level#
intermediate
Location#
src/mat/impls/centering/centering.c
Index of all Mat routines
Table of Contents for all manual pages
Index of all manual pages