KronA matrix-free product (Kamath Eq 4.7)

(A (x) B) x = gamma(B eta(x) A^T). Both folds are COLUMN-MAJOR, which is R's native matrix() layout and what makes the identity hold.

Usage

morie_kamath_ch4_krona_efficient(A, B, x)

Arguments

A, B

Factors.

x

Vector of length ncol(A) * ncol(B).

Value

List with y, folded_shape, products_avoided.

Examples

morie_kamath_ch4_krona_efficient(A = c(1, 2, 3, 4, 5, 6, 7, 8), B = 5L, x = 5L)
#> $y
#> [1]  25  50  75 100 125 150 175 200
#> 
#> $folded_shape
#> [1] 1 1
#> 
#> $estimate
#> [1] 25
#> 
#> $n
#> [1] 8
#> 
#> $products_avoided
#> [1] 8
#> 
#> $method
#> [1] "KronA matrix-free product (Kamath Eq 4.7)"
#>