R: Extract row and column indices, pointers and values from a...

Matrix.to.Pointers {sparseHessianFD}

R Documentation

Extract row and column indices, pointers and values from a sparse matrix.

Description

Returns a list of row indices, column indices, pointers, and/or values of a sparse Hessian.

Usage

Matrix.to.Pointers(
  M,
  as.symmetric = Matrix::isSymmetric(M),
  values = !is(M, "nMatrix"),
  order = NULL,
  index1 = TRUE
)

Arguments

`M`	A sparse Matrix, as defined in the Matrix package.
`as.symmetric`	Defaults to isSymmetric(M). If M is symmetric, and as.symmetric is FALSE, then index/pointer elements in the output list will be labeled according to order. If M is not symmetric, and as.symmetric is TRUE, then an error will be triggered.
`values`	If TRUE, values are returned in list as 'x'. Defaults to TRUE for numeric and logical matrices, and FALSE for pattern matrices. If M is a pattern matrix, values=TRUE will trigger a warning.
`order`	Determines the indexing/compression scheme for the output matrix. Use 'triplet" to get row and column indices. Defaults to the same class as M.
`index1`	TRUE (default) if return indices and pointers should use 1-based indexing. FALSE for 0-based indexing.

Details

This function is included primarily for debugging purposes. It is used internally, but would not ordinarily be called by an end user.

Value

A list with the following elements. If order=='row',

jCol: Integer vector containing column indices of non-zero elements
ipntr: Integer vector containing pointers to elements of jCol at which the next row begins.

If order=='column'

iRow: Integer vector containing row indices of non-zero elements
jpntr: Integer vector containing pointers to elements of iRow at which the next column begins.

If order=='triplet'

rows: Row indices of non-zero elements
cols: Column indices of non-zero elements

If as.symmetric is TRUE, then the row/column orientation does not matter.

idx: Integer vector containing indices of non-zero elements
pntr: Integer vector containing pointers to elements of idx at which the next row or column begins.