Program zspcon_example ! ZSPCON Example Program Text ! Copyright 2017, Numerical Algorithms Group Ltd. http://www.nag.com ! .. Use Statements .. Use lapack_interfaces, Only: zlansp, zspcon, zsptrf Use lapack_precision, Only: dp ! .. Implicit None Statement .. Implicit None ! .. Parameters .. Integer, Parameter :: nin = 5, nout = 6 ! .. Local Scalars .. Real (Kind=dp) :: anorm, rcond Integer :: i, info, j, n Character (1) :: uplo ! .. Local Arrays .. Complex (Kind=dp), Allocatable :: ap(:), work(:) Real (Kind=dp), Allocatable :: rwork(:) Integer, Allocatable :: ipiv(:) ! .. Intrinsic Procedures .. Intrinsic :: epsilon ! .. Executable Statements .. Write (nout, *) 'ZSPCON Example Program Results' ! Skip heading in data file Read (nin, *) Read (nin, *) n Allocate (ap(n*(n+1)/2), work(2*n), rwork(n), ipiv(n)) ! Read A from data file Read (nin, *) uplo If (uplo=='U') Then Read (nin, *)((ap(i+j*(j-1)/2),j=i,n), i=1, n) Else If (uplo=='L') Then Read (nin, *)((ap(i+(2*n-j)*(j-1)/2),j=1,i), i=1, n) End If ! Compute norm of A anorm = zlansp('1-norm', uplo, n, ap, rwork) ! Factorize A Call zsptrf(uplo, n, ap, ipiv, info) Write (nout, *) If (info==0) Then ! Estimate condition number Call zspcon(uplo, n, ap, ipiv, anorm, rcond, work, info) 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 Else Write (nout, *) 'The factor D is singular' End If 100 Format (1X, A, 1P, E10.2) End Program