Program f08kffe ! F08KFF Example Program Text ! Mark 24 Release. NAG Copyright 2012. ! .. Use Statements .. Use nag_library, Only: dbdsqr, dgebrd, dorgbr, f06qff, nag_wp, x04caf ! .. Implicit None Statement .. Implicit None ! .. Parameters .. Integer, Parameter :: nin = 5, nout = 6 ! .. Local Scalars .. Integer :: i, ic, ifail, info, lda, ldc, ldu, & ldvt, lwork, m, n ! .. Local Arrays .. Real (Kind=nag_wp), Allocatable :: a(:,:), c(:,:), d(:), e(:), taup(:), & tauq(:), u(:,:), vt(:,:), work(:) ! .. Executable Statements .. Write (nout,*) 'F08KFF Example Program Results' ! Skip heading in data file Read (nin,*) Do ic = 1, 2 Read (nin,*) m, n lda = m ldc = n ldu = m ldvt = n lwork = 64*(m+n) Allocate (a(lda,n),c(ldc,n),d(n),e(n-1),taup(n),tauq(n),u(ldu,n), & vt(ldvt,n),work(lwork)) ! Read A from data file Read (nin,*)(a(i,1:n),i=1,m) ! Reduce A to bidiagonal form ! The NAG name equivalent of dgebrd is f08kef Call dgebrd(m,n,a,lda,d,e,tauq,taup,work,lwork,info) If (m>=n) Then ! Copy A to VT and U Call f06qff('Upper',n,n,a,lda,vt,ldvt) Call f06qff('Lower',m,n,a,lda,u,ldu) ! Form P**T explicitly, storing the result in VT ! The NAG name equivalent of dorgbr is f08kff Call dorgbr('P',n,n,m,vt,ldvt,taup,work,lwork,info) ! Form Q explicitly, storing the result in U ! The NAG name equivalent of dorgbr is f08kff Call dorgbr('Q',m,n,n,u,ldu,tauq,work,lwork,info) ! Compute the SVD of A ! The NAG name equivalent of dbdsqr is f08mef Call dbdsqr('Upper',n,n,m,0,d,e,vt,ldvt,u,ldu,c,ldc,work,info) ! Print singular values, left & right singular vectors Write (nout,*) Write (nout,*) 'Example 1: singular values' Write (nout,99999) d(1:n) Write (nout,*) Flush (nout) ! ifail: behaviour on error exit ! =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft ifail = 0 Call x04caf('General',' ',n,n,vt,ldvt, & 'Example 1: right singular vectors, by row',ifail) Write (nout,*) Flush (nout) Call x04caf('General',' ',m,n,u,ldu, & 'Example 1: left singular vectors, by column',ifail) Else ! Copy A to VT and U Call f06qff('Upper',m,n,a,lda,vt,ldvt) Call f06qff('Lower',m,m,a,lda,u,ldu) ! Form P**T explicitly, storing the result in VT ! The NAG name equivalent of dorgbr is f08kff Call dorgbr('P',m,n,m,vt,ldvt,taup,work,lwork,info) ! Form Q explicitly, storing the result in U ! The NAG name equivalent of dorgbr is f08kff Call dorgbr('Q',m,m,n,u,ldu,tauq,work,lwork,info) ! Compute the SVD of A ! The NAG name equivalent of dbdsqr is f08mef Call dbdsqr('Lower',m,n,m,0,d,e,vt,ldvt,u,ldu,c,ldc,work,info) ! Print singular values, left & right singular vectors Write (nout,*) Write (nout,*) 'Example 2: singular values' Write (nout,99999) d(1:m) Write (nout,*) Flush (nout) ifail = 0 Call x04caf('General',' ',m,n,vt,ldvt, & 'Example 2: right singular vectors, by row',ifail) Write (nout,*) Flush (nout) Call x04caf('General',' ',m,m,u,ldu, & 'Example 2: left singular vectors, by column',ifail) End If Deallocate (a,c,d,e,taup,tauq,u,vt,work) End Do 99999 Format (3X,(8F8.4)) End Program f08kffe