PROGRAM f07pdfe ! F07PDF Example Program Text ! Mark 23 Release. NAG Copyright 2011. ! .. Use Statements .. USE nag_library, ONLY : dsptrf, nag_wp, x04ccf ! .. Implicit None Statement .. IMPLICIT NONE ! .. Parameters .. INTEGER, PARAMETER :: nin = 5, nout = 6 ! .. Local Scalars .. INTEGER :: i, ifail, info, j, n CHARACTER (1) :: uplo ! .. Local Arrays .. REAL (KIND=nag_wp), ALLOCATABLE :: ap(:) INTEGER, ALLOCATABLE :: ipiv(:) ! .. Executable Statements .. WRITE (nout,*) 'F07PDF Example Program Results' ! Skip heading in data file READ (nin,*) READ (nin,*) n ALLOCATE (ap(n*(n+1)/2),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 ! Factorize A ! The NAG name equivalent of dsptrf is f07pdf CALL dsptrf(uplo,n,ap,ipiv,info) WRITE (nout,*) FLUSH (nout) ! Print details of factorization ! ifail: behaviour on error exit ! =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft ifail = 0 CALL x04ccf(uplo,'Nonunit',n,ap,'Details of factorization',ifail) ! Print pivot indices WRITE (nout,*) WRITE (nout,*) 'IPIV' WRITE (nout,99999) ipiv(1:n) IF (info/=0) WRITE (nout,*) 'The factor D is singular' 99999 FORMAT ((3X,7I11)) END PROGRAM f07pdfe