Dlangb Dlange Dlangt Dlansb Dlansp Dlanst Dlansy Dlantr

Dlange() Function Dlange ( Norm As  String, M As  Long, N As  Long, A() As  Double, Optional Info As  Long  ) One norm, Frobenius norm, infinity norm, or largest absolute value of any element of a general rectangular matrix Purpose This routine returns the value of the one norm, the Frobenius norm, the infinity norm, or the largest absolute value of any element of a real matrix A. Returns Double max(abs(Aij)) when Norm = "M", norm1(A) when Norm = "1" or "O", normI(A) when Norm = "I", or normF(A) when Norm = "F" or "E" where norm1 denotes the one norm of a matrix (maximum column sum), normI denotes the infinity norm of a matrix (maximum row sum) and normF denotes the Frobenius norm of a matrix (square root of sum of squares). Note that max(abs(Aij)) is not a consistent matrix norm. Parameters [in] Norm Specifies the value to be returned by Dlange as described above. [in] M Number of rows of the matrix A. (M >= 0) (If M = 0, returns 0) [in] N Number of columns of the matrix A. (N >= 0) (If N = 0, returns 0) [in] A() Array A(LA1 - 1, LA2 - 1) (LA1 >= M, LA2 >= N) M x N matrix A. [out] Info (Optional) = 0: Successful exit. = -1: The argument Norm had an illegal value. (Norm <> "M", "1", "O", "I", "F" nor "E") = -2: The argument M had an illegal value. (M < 0) = -3: The argument N had an illegal value. (N < 0) = -4: The argument A() is invalid. Reference LAPACK Example Program Compute the norm of the matrix A, where ( 0.2 -0.11 -0.93 ) A = ( -0.32 0.81 0.37 ) ( -0.8 -0.92 -0.29 ) Sub Ex_Dlange() Const N As Long = 3 Dim A(N - 1, N - 1) As Double Dim ANormM As Double, ANorm1 As Double, ANormI As Double, ANormF As Double A(0, 0) = 0.2: A(0, 1) = -0.11: A(0, 2) = -0.93 A(1, 0) = -0.32: A(1, 1) = 0.81: A(1, 2) = 0.37 A(2, 0) = -0.8: A(2, 1) = -0.92: A(2, 2) = -0.29 ANormM = Dlange("M", N, N, A()) ANorm1 = Dlange("1", N, N, A()) ANormI = Dlange("I", N, N, A()) ANormF = Dlange("F", N, N, A()) Debug.Print "max(abs(Aij)), norm1(A), normI(A), normF(A) =" Debug.Print ANormM, ANorm1, ANormI, ANormF End Sub Example Results max(abs(Aij)), norm1(A), normI(A), normF(A) = 0.93 1.84 2.01 1.83926615800976