trilower(A), A a matrix |

trilower(a) returns a matrix d of the same size and shape as a with d[i,j] = a[i,j] for i >= j (on or below the diagonal) and d[i,j] = 0 for i < j (above the diagonal). Variable a must be a matrix but need not be square. [1 5 9] [1 0 0] For example, when a is [2 6 10] , trilower(a) is [2 6 0] . [3 7 11] [3 7 11] [4 8 12] [4 8 12] When a has type CHARACTER, elements above the diagonal are sent to empty strings ("") instead of 0's. trilower(a,T) or trilower(a,pack:T) returns the lower triangle (elements a[i,j] with i >= j) of a in packed form. Matrix a must be square, that is, nrows(a) = ncols(b). For example, when [1 4 7] a = [2 5 8] , [3 6 9] trilower(a) is vector(1, 2, 5, 3, 6, 9). Note: keyword 'square' is not valid for trilower(). See also triupper(), triunpack(), qr().

Gary Oehlert 2003-01-15