Contents
ssttrf - compute the factorization of a symmetric tridiago-
nal matrix A
SUBROUTINE SSTTRF(N, L, D, SUBL, IPIV, INFO)
INTEGER N, INFO
INTEGER IPIV(*)
REAL L(*), D(*), SUBL(*)
SUBROUTINE SSTTRF_64(N, L, D, SUBL, IPIV, INFO)
INTEGER*8 N, INFO
INTEGER*8 IPIV(*)
REAL L(*), D(*), SUBL(*)
F95 INTERFACE
SUBROUTINE STTRF([N], L, D, SUBL, IPIV, [INFO])
INTEGER :: N, INFO
INTEGER, DIMENSION(:) :: IPIV
REAL, DIMENSION(:) :: L, D, SUBL
SUBROUTINE STTRF_64([N], L, D, SUBL, IPIV, [INFO])
INTEGER(8) :: N, INFO
INTEGER(8), DIMENSION(:) :: IPIV
REAL, DIMENSION(:) :: L, D, SUBL
C INTERFACE
#include <sunperf.h>
void ssttrf(int n, float *l, float *d, float *subl, int
*ipiv, int *info);
void ssttrf_64(long n, float *l, float *d, float *subl, long
*ipiv, long *info);
ssttrf computes the factorization of a complex Hermitian
tridiagonal matrix A.
N (input) INTEGER
The order of the matrix A. N >= 0.
L (input/output)
REAL array, dimension (N)
On entry, the n-1 subdiagonal elements of the tri-
diagonal matrix A. On exit, part of the factori-
zation of A.
D (input/output)
REAL array, dimension (N)
On entry, the n diagonal elements of the tridiago-
nal matrix A. On exit, the n diagonal elements of
the diagonal matrix D from the L*D*L**H factoriza-
tion of A.
SUBL (output)
REAL array, dimension (N)
On exit, part of the factorization of A.
IPIV (output)
INTEGER array, dimension (N)
On exit, the pivot indices of the factorization.
INFO (output)
INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an ille-
gal value
> 0: if INFO = i, D(k,k) is exactly zero. The
factorization has been completed, but the block
diagonal matrix D is exactly singular and division
by zero will occur if it is used to solve a system
of equations.