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zsytri_example.f90
executable file
·65 lines (53 loc) · 1.89 KB
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zsytri_example.f90
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Program zsytri_example
! ZSYTRI Example Program Text
! Copyright (c) 2018, Numerical Algorithms Group (NAG Ltd.)
! For licence see
! https://github.com/numericalalgorithmsgroup/LAPACK_Examples/blob/master/LICENCE.md
! .. Use Statements ..
Use lapack_example_aux, Only: nagf_file_print_matrix_complex_gen_comp
Use lapack_interfaces, Only: zsytrf, zsytri
Use lapack_precision, Only: dp
! .. Implicit None Statement ..
Implicit None
! .. Parameters ..
Integer, Parameter :: nin = 5, nout = 6
! .. Local Scalars ..
Integer :: i, ifail, info, lda, lwork, n
Character (1) :: uplo
! .. Local Arrays ..
Complex (Kind=dp), Allocatable :: a(:, :), work(:)
Integer, Allocatable :: ipiv(:)
Character (1) :: clabs(1), rlabs(1)
! .. Executable Statements ..
Write (nout, *) 'ZSYTRI Example Program Results'
! Skip heading in data file
Read (nin, *)
Read (nin, *) n
lda = n
lwork = 64*n
Allocate (a(lda,n), work(lwork), ipiv(n))
! Read A from data file
Read (nin, *) uplo
If (uplo=='U') Then
Read (nin, *)(a(i,i:n), i=1, n)
Else If (uplo=='L') Then
Read (nin, *)(a(i,1:i), i=1, n)
End If
! Factorize A
Call zsytrf(uplo, n, a, lda, ipiv, work, lwork, info)
Write (nout, *)
Flush (nout)
If (info==0) Then
! Compute inverse of A
Call zsytri(uplo, n, a, lda, ipiv, work, info)
! Print inverse
! ifail: behaviour on error exit
! =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft
ifail = 0
Call nagf_file_print_matrix_complex_gen_comp(uplo, 'Nonunit', n, n, a, &
lda, 'Bracketed', 'F7.4', 'Inverse', 'Integer', rlabs, 'Integer', &
clabs, 80, 0, ifail)
Else
Write (nout, *) 'The factor D is singular'
End If
End Program