triupper(A [,pack:T]), A a matrix |

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

Gary Oehlert 2003-01-15