R: Matrix Crossproduct

crossprod {slam} | R Documentation

## Matrix Crossproduct

### Description

Compute the matrix cross-product of a sparse and a dense or sparse matrix.

### Usage

    tcrossprod_simple_triplet_matrix(x, y = NULL)
    ##
    crossprod_simple_triplet_matrix(x, y = NULL)
    matprod_simple_triplet_matrix(x, y)

### Arguments

`x, y` | a matrix in `simple_triplet_matrix`-form and/or a dense matrix, where one must be of the form indicated by the suffix.

### Details

Function `tcrossprod_simple_triplet_matrix` implements fast computation of `x %*% t(x)` and `x %*% t(y)` (`tcrossprod`). The remaining functions are (optimized) wrappers.

### Value

A double matrix, with appropriate `dimnames` taken from `x` and `y`.

### Note

The computation is delegated to `tcrossprod` if `y` (or `x` if `y == NULL`) contains any of the special values `NA`, `NaN`, or `Inf`.

### Author(s)

Christian Buchta

### See Also

`crossprod` for dense-on-dense computations.

### Examples

    ##
    x <- matrix(c(1, 0, 0, 2, 1, 0), nrow = 3)
    x
    s <- as.simple_triplet_matrix(x)
    tcrossprod_simple_triplet_matrix(s, x)
    ##
    tcrossprod_simple_triplet_matrix(s)
    ##
    tcrossprod_simple_triplet_matrix(s[1L, ], s[2:3, ])

[Package slam version 0.1-40 Index]