spttrs(3P) Sun Performance Library spttrs(3P)NAMEspttrs - solve a tridiagonal system of the form A * X = B using the
L*D*L' factorization of A computed by SPTTRF
SYNOPSIS
SUBROUTINE SPTTRS(N, NRHS, D, E, B, LDB, INFO)
INTEGER N, NRHS, LDB, INFO
REAL D(*), E(*), B(LDB,*)
SUBROUTINE SPTTRS_64(N, NRHS, D, E, B, LDB, INFO)
INTEGER*8 N, NRHS, LDB, INFO
REAL D(*), E(*), B(LDB,*)
F95 INTERFACE
SUBROUTINE PTTRS([N], [NRHS], D, E, B, [LDB], [INFO])
INTEGER :: N, NRHS, LDB, INFO
REAL, DIMENSION(:) :: D, E
REAL, DIMENSION(:,:) :: B
SUBROUTINE PTTRS_64([N], [NRHS], D, E, B, [LDB], [INFO])
INTEGER(8) :: N, NRHS, LDB, INFO
REAL, DIMENSION(:) :: D, E
REAL, DIMENSION(:,:) :: B
C INTERFACE
#include <sunperf.h>
void spttrs(int n, int nrhs, float *d, float *e, float *b, int ldb, int
*info);
void spttrs_64(long n, long nrhs, float *d, float *e, float *b, long
ldb, long *info);
PURPOSEspttrs solves a tridiagonal system of the form
A * X = B using the L*D*L' factorization of A computed by SPTTRF. D
is a diagonal matrix specified in the vector D, L is a unit bidiagonal
matrix whose subdiagonal is specified in the vector E, and X and B are
N by NRHS matrices.
ARGUMENTS
N (input) The order of the tridiagonal matrix A. N >= 0.
NRHS (input)
The number of right hand sides, i.e., the number of columns
of the matrix B. NRHS >= 0.
D (input) The n diagonal elements of the diagonal matrix D from the
L*D*L' factorization of A.
E (input) The (n-1) subdiagonal elements of the unit bidiagonal factor
L from the L*D*L' factorization of A. E can also be regarded
as the superdiagonal of the unit bidiagonal factor U from the
factorization A = U'*D*U.
B (input/output)
On entry, the right hand side vectors B for the system of
linear equations. On exit, the solution vectors, X.
LDB (input)
The leading dimension of the array B. LDB >= max(1,N).
INFO (output)
= 0: successful exit
< 0: if INFO = -k, the k-th argument had an illegal value
6 Mar 2009 spttrs(3P)
