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Generalised matrix multiply (BLAS DGEMM interface)

Source: R/wrappers.R
gemm.Rd

Computes alpha * op(A) %*% op(B) + beta * C, where op(X) = t(X) when the corresponding trans flag is TRUE. Routes internally to the most efficient resident operation for the chosen transpose combination.

Usage

gemm(A, B, C = NULL, alpha = 1, beta = 1, transA = FALSE, transB = FALSE)

Arguments

A

A matrix or aMatrix.

B

A matrix or aMatrix.

C

Optional matrix or aMatrix to add after scaling; NULL omits the addition term.

alpha

Numeric scalar multiplier for op(A) %*% op(B). Default 1.0.

beta

Numeric scalar multiplier for C. Default 1.0.

transA

Logical; transpose A before multiplying. Default FALSE.

transB

Logical; transpose B before multiplying. Default FALSE.

Value

A matrix of dimensions nrow(op(A)) by ncol(op(B)).

Examples

A <- adgeMatrix(matrix(1:6, 2, 3))
B <- adgeMatrix(matrix(1:6, 2, 3))
gemm(A, B, transA = TRUE)          # t(A) %*% B
#> An amatrix dense matrix [cpu|policy=auto|precision=strict]
#> 3 x 3 Matrix of class "adgeMatrix"
#>      [,1] [,2] [,3]
#> [1,]    5   11   17
#> [2,]   11   25   39
#> [3,]   17   39   61
gemm(A, B, transB = TRUE)          # A %*% t(B)
#> An amatrix dense matrix [cpu|policy=auto|precision=strict]
#> 2 x 2 Matrix of class "adgeMatrix"
#>      [,1] [,2]
#> [1,]   35   44
#> [2,]   44   56