PROGRAM f08bafe ! F08BAF Example Program Text ! Mark 23 Release. NAG Copyright 2011. ! .. Use Statements .. USE nag_library, ONLY : dgelsy, nag_wp ! .. Implicit None Statement .. IMPLICIT NONE ! .. Parameters .. INTEGER, PARAMETER :: nb = 64, nin = 5, nout = 6 ! .. Local Scalars .. REAL (KIND=nag_wp) :: rcond INTEGER :: i, info, lda, lwork, m, n, rank ! .. Local Arrays .. REAL (KIND=nag_wp), ALLOCATABLE :: a(:,:), b(:), work(:) INTEGER, ALLOCATABLE :: jpvt(:) ! .. Executable Statements .. WRITE (nout,*) 'F08BAF Example Program Results' WRITE (nout,*) ! Skip heading in data file READ (nin,*) READ (nin,*) m, n lda = m lwork = 3*n + nb*(n+1) ALLOCATE (a(lda,n),b(m),work(lwork),jpvt(n)) ! Read A and B from data file READ (nin,*) (a(i,1:n),i=1,m) READ (nin,*) b(1:m) ! Initialize JPVT to be zero so that all columns are free jpvt(1:n) = 0 ! Choose RCOND to reflect the relative accuracy of the input data rcond = 0.01_nag_wp ! Solve the least squares problem min( norm2(b - Ax) ) for the x ! of minimum norm. ! The NAG name equivalent of dgelsy is f08baf CALL dgelsy(m,n,1,a,lda,b,m,jpvt,rcond,rank,work,lwork,info) ! Print solution WRITE (nout,*) 'Least squares solution' WRITE (nout,99999) b(1:n) ! Print the effective rank of A WRITE (nout,*) WRITE (nout,*) 'Tolerance used to estimate the rank of A' WRITE (nout,99998) rcond WRITE (nout,*) 'Estimated rank of A' WRITE (nout,99997) rank 99999 FORMAT (1X,7F11.4) 99998 FORMAT (3X,1P,E11.2) 99997 FORMAT (1X,I6) END PROGRAM f08bafe