dsttrf - compute the factorization of a symmetric tridiagonal matrix A using the Bunch-Kaufman diagonal pivoting method
SUBROUTINE DSTTRF(N, L, D, SUBL, IPIV, INFO) INTEGER N, INFO INTEGER IPIV(*) DOUBLE PRECISION L(*), D(*), SUBL(*) SUBROUTINE DSTTRF_64(N, L, D, SUBL, IPIV, INFO) INTEGER*8 N, INFO INTEGER*8 IPIV(*) DOUBLE PRECISION L(*), D(*), SUBL(*) F95 INTERFACE SUBROUTINE STTRF(N, L, D, SUBL, IPIV, INFO) INTEGER :: N, INFO INTEGER, DIMENSION(:) :: IPIV REAL(8), DIMENSION(:) :: L, D, SUBL SUBROUTINE STTRF_64(N, L, D, SUBL, IPIV, INFO) INTEGER(8) :: N, INFO INTEGER(8), DIMENSION(:) :: IPIV REAL(8), DIMENSION(:) :: L, D, SUBL C INTERFACE #include <sunperf.h> void dsttrf(int n, double *l, double *d, double *subl, int *ipiv, int *info); void dsttrf_64(long n, double *l, double *d, double *subl, long *ipiv, long *info);
Oracle Solaris Studio Performance Library dsttrf(3P) NAME dsttrf - compute the factorization of a symmetric tridiagonal matrix A using the Bunch-Kaufman diagonal pivoting method SYNOPSIS SUBROUTINE DSTTRF(N, L, D, SUBL, IPIV, INFO) INTEGER N, INFO INTEGER IPIV(*) DOUBLE PRECISION L(*), D(*), SUBL(*) SUBROUTINE DSTTRF_64(N, L, D, SUBL, IPIV, INFO) INTEGER*8 N, INFO INTEGER*8 IPIV(*) DOUBLE PRECISION L(*), D(*), SUBL(*) F95 INTERFACE SUBROUTINE STTRF(N, L, D, SUBL, IPIV, INFO) INTEGER :: N, INFO INTEGER, DIMENSION(:) :: IPIV REAL(8), DIMENSION(:) :: L, D, SUBL SUBROUTINE STTRF_64(N, L, D, SUBL, IPIV, INFO) INTEGER(8) :: N, INFO INTEGER(8), DIMENSION(:) :: IPIV REAL(8), DIMENSION(:) :: L, D, SUBL C INTERFACE #include <sunperf.h> void dsttrf(int n, double *l, double *d, double *subl, int *ipiv, int *info); void dsttrf_64(long n, double *l, double *d, double *subl, long *ipiv, long *info); PURPOSE dsttrf computes the L*D*L' factorization of a real symmetric tridiago- nal matrix A using the Bunch-Kaufman diagonal pivoting method. ARGUMENTS N (input) INTEGER The order of the matrix A. N >= 0. L (input/output) REAL array, dimension (N-1) On entry, the n-1 subdiagonal elements of the tridiagonal matrix A. On exit, part of the factorization of A. D (input/output) REAL array, dimension (N) On entry, the n diagonal elements of the tridiagonal matrix A. On exit, the n diagonal elements of the diagonal matrix D from the L*D*L**H factorization of A. SUBL (output) REAL array, dimension (N-2) On exit, part of the factorization of A. IPIV (output) INTEGER array, dimension (N) Details of the interchanges and block pivot. If IPIV(K) > 0, 1 by 1 pivot, and if IPIV(K) = K + 1 an interchange done; If IPIV(K) < 0, 2 by 2 pivot, no interchange required. INFO (output) INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal 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. 7 Nov 2015 dsttrf(3P)