Row Cofactors of A[i,]

Source: R/determinants.R

rowCofactors.Rd

Returns the vector of cofactors of row i of the square matrix A. The determinant, Det(A), can then be found as M[i,] %*% rowCofactors(M,i) for any row, i.

Usage

rowCofactors(A, i)

Arguments

A: a square matrix
i: row index

Value

a vector of the cofactors of A[i,]

Author

Michael Friendly

Examples

M <- matrix (c (4, -12, -4,
 2, 1, 3,
 -1, -3, 2), 3, 3, byrow=TRUE)
minor (M, 1, 1)
#> [1] 11
minor (M, 1, 2)
#> [1] 7
minor (M, 1, 3)
#> [1] -5
rowCofactors(M, 1)
#> [1] 11 -7 -5
Det (M)
#> [1] 148
# expansion by cofactors of row 1
M[1,] %*%  rowCofactors(M,1)
#> [,1]
#> [1,] 148