stev(3)                    Library Functions Manual                    stev(3)

NAME
       stev - stev: eig, QR iteration

SYNOPSIS
   Functions
       subroutine dstev (jobz, n, d, e, z, ldz, work, info)
            DSTEV computes the eigenvalues and, optionally, the left and/or
           right eigenvectors for OTHER matrices
       subroutine sstev (jobz, n, d, e, z, ldz, work, info)
            SSTEV computes the eigenvalues and, optionally, the left and/or
           right eigenvectors for OTHER matrices

Detailed Description
Function Documentation
   subroutine dstev (character jobz, integer n, double precision, dimension( *
       ) d, double precision, dimension( * ) e, double precision, dimension(
       ldz, * ) z, integer ldz, double precision, dimension( * ) work, integer
       info)
        DSTEV computes the eigenvalues and, optionally, the left and/or right
       eigenvectors for OTHER matrices

       Purpose:


            DSTEV computes all eigenvalues and, optionally, eigenvectors of a
            real symmetric tridiagonal matrix A.

       Parameters
           JOBZ

                     JOBZ is CHARACTER*1
                     = 'N':  Compute eigenvalues only;
                     = 'V':  Compute eigenvalues and eigenvectors.

           N

                     N is INTEGER
                     The order of the matrix.  N >= 0.

           D

                     D is DOUBLE PRECISION array, dimension (N)
                     On entry, the n diagonal elements of the tridiagonal matrix
                     A.
                     On exit, if INFO = 0, the eigenvalues in ascending order.

           E

                     E is DOUBLE PRECISION array, dimension (N-1)
                     On entry, the (n-1) subdiagonal elements of the tridiagonal
                     matrix A, stored in elements 1 to N-1 of E.
                     On exit, the contents of E are destroyed.

           Z

                     Z is DOUBLE PRECISION array, dimension (LDZ, N)
                     If JOBZ = 'V', then if INFO = 0, Z contains the orthonormal
                     eigenvectors of the matrix A, with the i-th column of Z
                     holding the eigenvector associated with D(i).
                     If JOBZ = 'N', then Z is not referenced.

           LDZ

                     LDZ is INTEGER
                     The leading dimension of the array Z.  LDZ >= 1, and if
                     JOBZ = 'V', LDZ >= max(1,N).

           WORK

                     WORK is DOUBLE PRECISION array, dimension (max(1,2*N-2))
                     If JOBZ = 'N', WORK is not referenced.

           INFO

                     INFO is INTEGER
                     = 0:  successful exit
                     < 0:  if INFO = -i, the i-th argument had an illegal value
                     > 0:  if INFO = i, the algorithm failed to converge; i
                           off-diagonal elements of E did not converge to zero.

       Author
           Univ. of Tennessee

           Univ. of California Berkeley

           Univ. of Colorado Denver

           NAG Ltd.

       Definition at line 115 of file dstev.f.

   subroutine sstev (character jobz, integer n, real, dimension( * ) d, real,
       dimension( * ) e, real, dimension( ldz, * ) z, integer ldz, real,
       dimension( * ) work, integer info)
        SSTEV computes the eigenvalues and, optionally, the left and/or right
       eigenvectors for OTHER matrices

       Purpose:


            SSTEV computes all eigenvalues and, optionally, eigenvectors of a
            real symmetric tridiagonal matrix A.

       Parameters
           JOBZ

                     JOBZ is CHARACTER*1
                     = 'N':  Compute eigenvalues only;
                     = 'V':  Compute eigenvalues and eigenvectors.

           N

                     N is INTEGER
                     The order of the matrix.  N >= 0.

           D

                     D is REAL array, dimension (N)
                     On entry, the n diagonal elements of the tridiagonal matrix
                     A.
                     On exit, if INFO = 0, the eigenvalues in ascending order.

           E

                     E is REAL array, dimension (N-1)
                     On entry, the (n-1) subdiagonal elements of the tridiagonal
                     matrix A, stored in elements 1 to N-1 of E.
                     On exit, the contents of E are destroyed.

           Z

                     Z is REAL array, dimension (LDZ, N)
                     If JOBZ = 'V', then if INFO = 0, Z contains the orthonormal
                     eigenvectors of the matrix A, with the i-th column of Z
                     holding the eigenvector associated with D(i).
                     If JOBZ = 'N', then Z is not referenced.

           LDZ

                     LDZ is INTEGER
                     The leading dimension of the array Z.  LDZ >= 1, and if
                     JOBZ = 'V', LDZ >= max(1,N).

           WORK

                     WORK is REAL array, dimension (max(1,2*N-2))
                     If JOBZ = 'N', WORK is not referenced.

           INFO

                     INFO is INTEGER
                     = 0:  successful exit
                     < 0:  if INFO = -i, the i-th argument had an illegal value
                     > 0:  if INFO = i, the algorithm failed to converge; i
                           off-diagonal elements of E did not converge to zero.

       Author
           Univ. of Tennessee

           Univ. of California Berkeley

           Univ. of Colorado Denver

           NAG Ltd.

       Definition at line 115 of file sstev.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

LAPACK                          Version 3.12.0                         stev(3)