Program f07pbfe ! F07PBF Example Program Text ! Mark 24 Release. NAG Copyright 2012. ! .. Use Statements .. Use nag_library, Only: dspsvx, nag_wp, x04caf ! .. 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, ldb, ldx, n, nrhs ! .. Local Arrays .. Real (Kind=nag_wp), Allocatable :: afp(:), ap(:), b(:,:), berr(:), & ferr(:), work(:), x(:,:) Integer, Allocatable :: ipiv(:), iwork(:) ! .. Executable Statements .. Write (nout,*) 'F07PBF Example Program Results' Write (nout,*) Flush (nout) ! Skip heading in data file Read (nin,*) Read (nin,*) n, nrhs ldb = n ldx = n Allocate (afp((n*(n+1))/2),ap((n*(n+1))/2),b(ldb,nrhs),berr(nrhs),ferr( & nrhs),work(3*n),x(ldx,nrhs),ipiv(n),iwork(n)) ! Read the upper or lower triangular part of the matrix A from ! data file 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 ! 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 dspsvx is f07pbf Call dspsvx('Not factored',uplo,n,nrhs,ap,afp,ipiv,b,ldb,x,ldx,rcond, & ferr,berr,work,iwork,info) If ((info==0) .Or. (info==n+1)) Then ! Print solution, error bounds and condition number ! ifail: behaviour on error exit ! =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft ifail = 0 Call x04caf('General',' ',n,nrhs,x,ldx,'Solution(s)',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 (info==n+1) Then Write (nout,*) Write (nout,*) 'The matrix A is singular to working precision' End If Else Write (nout,99998) 'The diagonal block ', info, ' of D is zero' End If 99999 Format ((3X,1P,7E11.1)) 99998 Format (1X,A,I3,A) End Program f07pbfe