set off-diagonal values of a matrix
setMatrixOffDiagonals(x, diag = 1:length(value), value, isSymmetric = FALSE)
numeric square matrix
integer vector specifying the diagonals 0 is the center +1 the first row to upper and -2 the second row to lower
numeric vector of values to fill in
set to TRUE to to only specify the upper diagonal element but also set the lower in the mirrored diagonal
matrix with modified diagonal elements