dsterf

NAME

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

SYNOPSIS

  SUBROUTINE DSTERF( N, D, E, INFO)
  INTEGER N, INFO
  DOUBLE PRECISION D(*), E(*)
 
  SUBROUTINE DSTERF_64( N, D, E, INFO)
  INTEGER*8 N, INFO
  DOUBLE PRECISION D(*), E(*)

F95 INTERFACE

  SUBROUTINE STERF( [N], D, E, [INFO])
  INTEGER :: N, INFO
  REAL(8), DIMENSION(:) :: D, E
 
  SUBROUTINE STERF_64( [N], D, E, [INFO])
  INTEGER(8) :: N, INFO
  REAL(8), DIMENSION(:) :: D, E

C INTERFACE

#include <sunperf.h>

void dsterf(int n, double *d, double *e, int *info);

void dsterf_64(long n, double *d, double *e, long *info);

PURPOSE

dsterf 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 tridiagonal 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 destroyed.
* INFO (output)