Program f07hpfe ! F07HPF Example Program Text ! Mark 24 Release. NAG Copyright 2012. ! .. Use Statements .. Use nag_library, Only: nag_wp, x04dbf, zpbsvx ! .. Implicit None Statement .. Implicit None ! .. Parameters .. Integer, Parameter :: nin = 5, nout = 6 Character (1), Parameter :: uplo = 'U' ! .. Local Scalars .. Real (Kind=nag_wp) :: rcond Integer :: i, ifail, info, j, kd, ldab, ldafb, & ldb, ldx, n, nrhs Character (1) :: equed ! .. Local Arrays .. Complex (Kind=nag_wp), Allocatable :: ab(:,:), afb(:,:), b(:,:), & work(:), x(:,:) Real (Kind=nag_wp), Allocatable :: berr(:), ferr(:), rwork(:), s(:) Character (1) :: clabs(1), rlabs(1) ! .. Intrinsic Procedures .. Intrinsic :: max, min ! .. Executable Statements .. Write (nout,*) 'F07HPF Example Program Results' Write (nout,*) Flush (nout) ! Skip heading in data file Read (nin,*) Read (nin,*) n, kd, nrhs ldab = kd + 1 ldafb = kd + 1 ldb = n ldx = n Allocate (ab(ldab,n),afb(ldafb,n),b(ldb,nrhs),work(3*n),x(ldx,nrhs), & berr(nrhs),ferr(nrhs),rwork(n),s(n)) ! Read the upper or lower triangular part of the band matrix A ! from data file If (uplo=='U') Then Read (nin,*)((ab(kd+1+i-j,j),j=i,min(n,i+kd)),i=1,n) Else If (uplo=='L') Then Read (nin,*)((ab(1+i-j,j),j=max(1,i-kd),i),i=1,n) End If ! Read B from data file Read (nin,*)(b(i,1:nrhs),i=1,n) ! Solve the equations AX = B for X ! The NAG name equivalent of zpbsvx is f07hpf Call zpbsvx('Equilibration',uplo,n,kd,nrhs,ab,ldab,afb,ldafb,equed,s,b, & ldb,x,ldx,rcond,ferr,berr,work,rwork,info) If ((info==0) .Or. (info==n+1)) Then ! Print solution, error bounds, condition number and the form ! of equilibration ! ifail: behaviour on error exit ! =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft ifail = 0 Call x04dbf('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,99999) berr(1:nrhs) Write (nout,*) Write (nout,*) 'Estimated forward error bounds (machine-dependent)' Write (nout,99999) ferr(1:nrhs) Write (nout,*) Write (nout,*) 'Estimate of reciprocal condition number' Write (nout,99999) rcond Write (nout,*) If (equed=='N') Then Write (nout,*) 'A has not been equilibrated' Else If (equed=='Y') Then Write (nout,*) & 'A has been row and column scaled as diag(S)*A*diag(S)' End If If (info==n+1) Then Write (nout,*) Write (nout,*) 'The matrix A is singular to working precision' End If Else Write (nout,99998) 'The leading minor of order ', info, & ' is not positive definite' End If 99999 Format ((3X,1P,7E11.1)) 99998 Format (1X,A,I3,A) End Program f07hpfe