Program f04lefe ! F04LEF Example Program Text ! Mark 24 Release. NAG Copyright 2012. ! .. Use Statements .. Use nag_library, Only: f01lef, f04lef, nag_wp ! .. Implicit None Statement .. Implicit None ! .. Parameters .. Integer, Parameter :: nin = 5, nout = 6 ! .. Local Scalars .. Real (Kind=nag_wp) :: lambda, tol Integer :: ifail, job, n ! .. Local Arrays .. Real (Kind=nag_wp), Allocatable :: a(:), b(:), c(:), d(:), y(:), z(:) Integer, Allocatable :: ipiv(:) ! .. Executable Statements .. Write (nout,*) 'F04LEF Example Program Results' Write (nout,*) ! Skip heading in data file Read (nin,*) Read (nin,*) n Allocate (a(n),b(n),c(n),d(n),y(n),z(n),ipiv(n)) Read (nin,*) a(1:n) If (n>1) Then Read (nin,*) b(2:n) Read (nin,*) c(2:n) End If tol = 5.0E-5_nag_wp lambda = 0.0E0_nag_wp ! ifail: behaviour on error exit ! =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft ifail = 0 Call f01lef(n,a,lambda,b,c,tol,d,ipiv,ifail) If (ipiv(n)/=0) Then Write (nout,*) 'Matrix is singular or nearly singular' Write (nout,99999) 'Diagonal element', ipiv(n), 'is small' Else Read (nin,*) y(1:n) z(1:n) = y(1:n) job = 1 ifail = 0 Call f04lef(job,n,a,b,c,d,ipiv,y,tol,ifail) Write (nout,*) Write (nout,*) 'Solution vector for T*X = Y' Write (nout,99998) y(1:n) job = 2 ifail = 0 Call f04lef(job,n,a,b,c,d,ipiv,z,tol,ifail) Write (nout,*) Write (nout,*) 'Solution vector for transpose(T)*X = Y' Write (nout,99998) z(1:n) End If 99999 Format (1X,A,I4,A) 99998 Format (1X,5F9.3) End Program f04lefe