PROGRAM f07fnfe ! F07FNF Example Program Text ! Mark 23 Release. NAG Copyright 2011. ! .. Use Statements .. USE nag_library, ONLY : nag_wp, x04dbf, zposv ! .. Implicit None Statement .. IMPLICIT NONE ! .. Parameters .. INTEGER, PARAMETER :: nin = 5, nout = 6 ! .. Local Scalars .. INTEGER :: i, ifail, info, lda, n ! .. Local Arrays .. COMPLEX (KIND=nag_wp), ALLOCATABLE :: a(:,:), b(:) CHARACTER (1) :: clabs(1), rlabs(1) ! .. Executable Statements .. WRITE (nout,*) 'F07FNF Example Program Results' WRITE (nout,*) FLUSH (nout) ! Skip heading in data file READ (nin,*) READ (nin,*) n lda = n ALLOCATE (a(lda,n),b(n)) ! Read the upper triangular part of A from data file READ (nin,*) (a(i,i:n),i=1,n) ! Read b from data file READ (nin,*) b(1:n) ! Solve the equations Ax = b for x ! The NAG name equivalent of zposv is f07fnf CALL zposv('Upper',n,1,a,lda,b,n,info) IF (info==0) THEN ! Print solution WRITE (nout,*) 'Solution' WRITE (nout,99999) b(1:n) ! Print details of factorization WRITE (nout,*) FLUSH (nout) ! ifail: behaviour on error exit ! =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft ifail = 0 CALL x04dbf('Upper','Non-unit diagonal',n,n,a,lda,'Bracketed', & 'F7.4','Cholesky factor U','Integer',rlabs,'Integer',clabs,80,0, & ifail) ELSE WRITE (nout,99998) 'The leading minor of order ', info, & ' is not positive definite' END IF 99999 FORMAT ((3X,4(' (',F7.4,',',F7.4,')':))) 99998 FORMAT (1X,A,I3,A) END PROGRAM f07fnfe