sterf(3)                   Library Functions Manual                   sterf(3)

NAME
       sterf - sterf: eig, QR iteration

SYNOPSIS
   Functions
       subroutine dsterf (n, d, e, info)
           DSTERF
       subroutine ssterf (n, d, e, info)
           SSTERF

Detailed Description
Function Documentation
   subroutine dsterf (integer n, double precision, dimension( * ) d, double
       precision, dimension( * ) e, integer info)
       DSTERF

       Purpose:


            DSTERF computes all eigenvalues of a symmetric tridiagonal matrix
            using the Pal-Walker-Kahan variant of the QL or QR algorithm.

       Parameters
           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.
                     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.
                     On exit, E has been destroyed.

           INFO

                     INFO is INTEGER
                     = 0:  successful exit
                     < 0:  if INFO = -i, the i-th argument had an illegal value
                     > 0:  the algorithm failed to find all of the eigenvalues in
                           a total of 30*N iterations; if INFO = i, then i
                           elements of E have not converged to zero.

       Author
           Univ. of Tennessee

           Univ. of California Berkeley

           Univ. of Colorado Denver

           NAG Ltd.

       Definition at line 85 of file dsterf.f.

   subroutine ssterf (integer n, real, dimension( * ) d, real, dimension( * )
       e, integer info)
       SSTERF

       Purpose:


            SSTERF computes all eigenvalues of a symmetric tridiagonal matrix
            using the Pal-Walker-Kahan variant of the QL or QR algorithm.

       Parameters
           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.
                     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.
                     On exit, E has been destroyed.

           INFO

                     INFO is INTEGER
                     = 0:  successful exit
                     < 0:  if INFO = -i, the i-th argument had an illegal value
                     > 0:  the algorithm failed to find all of the eigenvalues in
                           a total of 30*N iterations; if INFO = i, then i
                           elements of E have not converged to zero.

       Author
           Univ. of Tennessee

           Univ. of California Berkeley

           Univ. of Colorado Denver

           NAG Ltd.

       Definition at line 85 of file ssterf.f.

Author
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LAPACK                          Version 3.12.0                        sterf(3)