cgtsv (3p)

Name

cgtsv - N tridiagonal matrix, by Gaussian elimination with partial pivoting

Synopsis

SUBROUTINE CGTSV(N, NRHS, LOW, D, UP, B, LDB, INFO)

COMPLEX LOW(*), D(*), UP(*), B(LDB,*)
INTEGER N, NRHS, LDB, INFO

SUBROUTINE CGTSV_64(N, NRHS, LOW, D, UP, B, LDB, INFO)

COMPLEX LOW(*), D(*), UP(*), B(LDB,*)
INTEGER*8 N, NRHS, LDB, INFO




F95 INTERFACE
SUBROUTINE GTSV(N, NRHS, LOW, D, UP, B, LDB, INFO)

COMPLEX, DIMENSION(:) :: LOW, D, UP
COMPLEX, DIMENSION(:,:) :: B
INTEGER :: N, NRHS, LDB, INFO

SUBROUTINE GTSV_64(N, NRHS, LOW, D, UP, B, LDB, INFO)

COMPLEX, DIMENSION(:) :: LOW, D, UP
COMPLEX, DIMENSION(:,:) :: B
INTEGER(8) :: N, NRHS, LDB, INFO




C INTERFACE
#include <sunperf.h>

void cgtsv(int n, int nrhs, complex *low, complex *d, complex *up, com-
plex *b, int ldb, int *info);

void cgtsv_64(long n, long nrhs, complex *low, complex *d, complex *up,
complex *b, long ldb, long *info);

Description

Oracle Solaris Studio Performance Library                            cgtsv(3P)



NAME
       cgtsv  -  solve  the equation A*X = B, where A is an N-by-N tridiagonal
       matrix, by Gaussian elimination with partial pivoting


SYNOPSIS
       SUBROUTINE CGTSV(N, NRHS, LOW, D, UP, B, LDB, INFO)

       COMPLEX LOW(*), D(*), UP(*), B(LDB,*)
       INTEGER N, NRHS, LDB, INFO

       SUBROUTINE CGTSV_64(N, NRHS, LOW, D, UP, B, LDB, INFO)

       COMPLEX LOW(*), D(*), UP(*), B(LDB,*)
       INTEGER*8 N, NRHS, LDB, INFO




   F95 INTERFACE
       SUBROUTINE GTSV(N, NRHS, LOW, D, UP, B, LDB, INFO)

       COMPLEX, DIMENSION(:) :: LOW, D, UP
       COMPLEX, DIMENSION(:,:) :: B
       INTEGER :: N, NRHS, LDB, INFO

       SUBROUTINE GTSV_64(N, NRHS, LOW, D, UP, B, LDB, INFO)

       COMPLEX, DIMENSION(:) :: LOW, D, UP
       COMPLEX, DIMENSION(:,:) :: B
       INTEGER(8) :: N, NRHS, LDB, INFO




   C INTERFACE
       #include <sunperf.h>

       void cgtsv(int n, int nrhs, complex *low, complex *d, complex *up, com-
                 plex *b, int ldb, int *info);

       void cgtsv_64(long n, long nrhs, complex *low, complex *d, complex *up,
                 complex *b, long ldb, long *info);



PURPOSE
       cgtsv solves the equation A*X=B,  where  A  is  an  N-by-N  tridiagonal
       matrix, by Gaussian elimination with partial pivoting.

       Note  that  the  equation   A'*X=B   may be solved by interchanging the
       order of the arguments DU and DL.


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


       NRHS (input)
                 The number of right hand sides, i.e., the number  of  columns
                 of the matrix B.  NRHS >= 0.


       LOW (input/output)
                 On  entry, LOW must contain the (n-1) subdiagonal elements of
                 A.  On exit, LOW is overwritten by the (n-2) elements of  the
                 second  superdiagonal  of  the upper triangular matrix U from
                 the LU factorization of A, in LOW(1), ..., LOW(n-2).


       D (input/output)
                 On entry, D must contain the  diagonal  elements  of  A.   On
                 exit, D is overwritten by the n diagonal elements of U.


       UP (input/output)
                 On entry, UP must contain the (n-1) superdiagonal elements of
                 A.  On exit, UP is overwritten by the (n-1) elements  of  the
                 first superdiagonal of U.


       B (input/output)
                 On  entry,  the N-by-NRHS right hand side matrix B.  On exit,
                 if INFO = 0, the N-by-NRHS solution matrix X.


       LDB (input)
                 The leading dimension of the array B.  LDB >= max(1,N).


       INFO (output)
                 = 0:  successful exit
                 < 0:  if INFO = -i, the i-th argument had an illegal value
                 > 0:  if INFO = i, U(i,i) is exactly zero, and  the  solution
                 has  not  been computed.  The factorization has not been com-
                 pleted unless i = N.



                                  7 Nov 2015                         cgtsv(3P)