Program f08aafe ! F08AAF Example Program Text ! Mark 24 Release. NAG Copyright 2012. ! .. Use Statements .. Use nag_library, Only: dgels, dnrm2, nag_wp ! .. Implicit None Statement .. Implicit None ! .. Parameters .. Integer, Parameter :: nb = 64, nin = 5, nout = 6 ! .. Local Scalars .. Real (Kind=nag_wp) :: rnorm Integer :: i, info, lda, ldb, lwork, m, n, nrhs ! .. Local Arrays .. Real (Kind=nag_wp), Allocatable :: a(:,:), b(:), work(:) ! .. Executable Statements .. Write (nout,*) 'F08AAF Example Program Results' Write (nout,*) ! Skip heading in data file Read (nin,*) Read (nin,*) m, n lda = m lwork = n + nb*m Allocate (a(lda,n),b(m),work(lwork)) ! Read A and B from data file Read (nin,*)(a(i,1:n),i=1,m) Read (nin,*) b(1:m) ! Solve the least squares problem min( norm2(b - Ax) ) for x nrhs = 1 ldb = m ! The NAG name equivalent of dgels is f08aaf Call dgels('No transpose',m,n,nrhs,a,lda,b,ldb,work,lwork,info) ! Print solution Write (nout,*) 'Least squares solution' Write (nout,99999) b(1:n) ! Compute and print estimate of the square root of the residual ! sum of squares ! The NAG name equivalent of dnrm2 is f06ejf rnorm = dnrm2(m-n,b(n+1),1) Write (nout,*) Write (nout,*) 'Square root of the residual sum of squares' Write (nout,99998) rnorm 99999 Format (1X,7F11.4) 99998 Format (3X,1P,E11.2) End Program f08aafe