subroutine rsm(nm,n,a,w,m,z,fwork,iwork,ierr) c integer n,nm,m,iwork(n),ierr integer k1,k2,k3,k4,k5,k6,k7 double precision a(nm,n),w(n),z(nm,m),fwork(1) c c this subroutine calls the recommended sequence of c subroutines from the eigensystem subroutine package (eispack) c to find all of the eigenvalues and some of the eigenvectors c of a real symmetric matrix. c c on input c c nm must be set to the row dimension of the two-dimensional c array parameters as declared in the calling program c dimension statement. c c n is the order of the matrix a. c c a contains the real symmetric matrix. c c m the eigenvectors corresponding to the first m eigenvalues c are to be computed. c if m = 0 then no eigenvectors are computed. c if m = n then all of the eigenvectors are computed. c c on output c c w contains all n eigenvalues in ascending order. c c z contains the orthonormal eigenvectors associated with c the first m eigenvalues. c c ierr is an integer output variable set equal to an error c completion code described in the documentation for tqlrat, c imtqlv and tinvit. the normal completion code is zero. c c fwork is a temporary storage array of dimension 8*n. c c iwork is an integer temporary storage array of dimension n. c c questions and comments should be directed to burton s. garbow, c mathematics and computer science div, argonne national laboratory c c this version dated august 1983. c c ------------------------------------------------------------------ c ierr = 10 * n if (n .gt. nm .or. m .gt. nm) go to 50 k1 = 1 k2 = k1 + n k3 = k2 + n k4 = k3 + n k5 = k4 + n k6 = k5 + n k7 = k6 + n k8 = k7 + n if (m .gt. 0) go to 10 c .......... find eigenvalues only .......... call tred1(nm,n,a,w,fwork(k1),fwork(k2)) call tqlrat(n,w,fwork(k2),ierr) go to 50 c .......... find all eigenvalues and m eigenvectors .......... 10 call tred1(nm,n,a,fwork(k1),fwork(k2),fwork(k3)) call imtqlv(n,fwork(k1),fwork(k2),fwork(k3),w,iwork, x ierr,fwork(k4)) call tinvit(nm,n,fwork(k1),fwork(k2),fwork(k3),m,w,iwork,z,ierr, x fwork(k4),fwork(k5),fwork(k6),fwork(k7),fwork(k8)) call trbak1(nm,n,a,fwork(k2),m,z) 50 return end