Program zherfs_example ! ZHERFS Example Program Text ! Copyright 2017, Numerical Algorithms Group Ltd. http://www.nag.com ! .. Use Statements .. Use lapack_example_aux, Only: nagf_file_print_matrix_complex_gen_comp Use lapack_interfaces, Only: zherfs, zhetrf, zhetrs, zlacpy Use lapack_precision, Only: dp ! .. Implicit None Statement .. Implicit None ! .. Parameters .. Integer, Parameter :: nin = 5, nout = 6 ! .. Local Scalars .. Integer :: i, ifail, info, lda, ldaf, ldb, ldx, lwork, n, nrhs Character (1) :: uplo ! .. Local Arrays .. Complex (Kind=dp), Allocatable :: a(:, :), af(:, :), b(:, :), work(:), & x(:, :) Real (Kind=dp), Allocatable :: berr(:), ferr(:), rwork(:) Integer, Allocatable :: ipiv(:) Character (1) :: clabs(1), rlabs(1) ! .. Executable Statements .. Write (nout, *) 'ZHERFS Example Program Results' ! Skip heading in data file Read (nin, *) Read (nin, *) n, nrhs lda = n ldaf = n ldb = n ldx = n lwork = 64*n Allocate (a(lda,n), af(ldaf,n), b(ldb,nrhs), work(lwork), x(ldx,n), & berr(nrhs), ferr(nrhs), rwork(n), ipiv(n)) ! Read A and B from data file, and copy A to AF and B to X 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 Read (nin, *)(b(i,1:nrhs), i=1, n) Call zlacpy(uplo, n, n, a, lda, af, ldaf) x(1:n, 1:nrhs) = b(1:n, 1:nrhs) ! Factorize A in the array AF Call zhetrf(uplo, n, af, ldaf, ipiv, work, lwork, info) Write (nout, *) Flush (nout) If (info==0) Then ! Compute solution in the array X Call zhetrs(uplo, n, nrhs, af, ldaf, ipiv, x, ldx, info) ! Improve solution, and compute backward errors and ! estimated bounds on the forward errors Call zherfs(uplo, n, nrhs, a, lda, af, ldaf, ipiv, b, ldb, x, ldx, & ferr, berr, work, rwork, info) ! Print solution ! 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('General', ' ', n, nrhs, & x, ldx, 'Bracketed', 'F7.4', 'Solution(s)', 'Integer', rlabs, & 'Integer', clabs, 80, 0, ifail) Write (nout, *) Write (nout, *) 'Backward errors (machine-dependent)' Write (nout, 100) berr(1:nrhs) Write (nout, *) 'Estimated forward error bounds (machine-dependent)' Write (nout, 100) ferr(1:nrhs) Else Write (nout, *) 'The factor D is singular' End If 100 Format ((5X,1P,4(E11.1,7X))) End Program