Contents

• NAME
• SYNOPSIS
  • F95 INTERFACE
  • C INTERFACE
• PURPOSE
• ARGUMENTS

NAME

     ssterf - compute all eigenvalues of a symmetric  tridiagonal
     matrix  using  the  Pal-Walker-Kahan variant of the QL or QR
     algorithm

SYNOPSIS

     SUBROUTINE SSTERF(N, D, E, INFO)

     INTEGER N, INFO
     REAL D(*), E(*)

     SUBROUTINE SSTERF_64(N, D, E, INFO)

     INTEGER*8 N, INFO
     REAL D(*), E(*)

  F95 INTERFACE
     SUBROUTINE STERF([N], D, E, [INFO])

     INTEGER :: N, INFO
     REAL, DIMENSION(:) :: D, E

     SUBROUTINE STERF_64([N], D, E, [INFO])

     INTEGER(8) :: N, INFO
     REAL, DIMENSION(:) :: D, E

  C INTERFACE
     #include <sunperf.h>

     void ssterf(int n, float *d, float *e, int *info);

     void ssterf_64(long n, float *d, float *e, long *info);

PURPOSE

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

ARGUMENTS

     N (input) The order of the matrix.  N >= 0.

     D (input/output)
               On entry, the n diagonal elements of the tridiago-
               nal matrix.  On exit, if INFO = 0, the eigenvalues
               in ascending order.

     E (input/output)
               On entry, the (n-1) subdiagonal  elements  of  the
               tridiagonal  matrix.   On  exit,  E  has been des-
               troyed.

     INFO (output)
               = 0:  successful exit
               < 0:  if INFO = -i, the i-th argument had an ille-
               gal 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.