Program ztbcon_example ! ZTBCON Example Program Text ! Copyright 2017, Numerical Algorithms Group Ltd. http://www.nag.com ! .. Use Statements .. Use lapack_interfaces, Only: ztbcon Use lapack_precision, Only: dp ! .. Implicit None Statement .. Implicit None ! .. Parameters .. Integer, Parameter :: nin = 5, nout = 6 Character (1), Parameter :: diag = 'N', norm = '1' ! .. Local Scalars .. Real (Kind=dp) :: rcond Integer :: i, info, j, kd, ldab, n Character (1) :: uplo ! .. Local Arrays .. Complex (Kind=dp), Allocatable :: ab(:, :), work(:) Real (Kind=dp), Allocatable :: rwork(:) ! .. Intrinsic Procedures .. Intrinsic :: epsilon, max, min ! .. Executable Statements .. Write (nout, *) 'ZTBCON Example Program Results' ! Skip heading in data file Read (nin, *) Read (nin, *) n, kd ldab = kd + 1 Allocate (ab(ldab,n), work(2*n), rwork(n)) ! Read A from data file Read (nin, *) uplo If (uplo=='U') Then Do i = 1, n Read (nin, *)(ab(kd+1+i-j,j), j=i, min(n,i+kd)) End Do Else If (uplo=='L') Then Do i = 1, n Read (nin, *)(ab(1+i-j,j), j=max(1,i-kd), i) End Do End If ! Estimate condition number Call ztbcon(norm, uplo, diag, n, kd, ab, ldab, rcond, work, rwork, info) Write (nout, *) If (rcond>=epsilon(1.0E0_dp)) Then Write (nout, 100) 'Estimate of condition number =', 1.0E0_dp/rcond Else Write (nout, *) 'A is singular to working precision' End If 100 Format (1X, A, 1P, E10.2) End Program