Contents

• NAME
• SYNOPSIS
  • F95 INTERFACE
  • C INTERFACE
• PURPOSE
• ARGUMENTS

NAME

     cgbtrs - solve a system of linear equations  A * X = B, A**T
     *  X = B, or A**H * X = B with a general band matrix A using
     the LU factorization computed by CGBTRF

SYNOPSIS

     SUBROUTINE CGBTRS(TRANSA, N, KL, KU, NRHS, A, LDA, IPIVOT, B,
           LDB, INFO)

     CHARACTER * 1 TRANSA
     COMPLEX A(LDA,*), B(LDB,*)
     INTEGER N, KL, KU, NRHS, LDA, LDB, INFO
     INTEGER IPIVOT(*)

     SUBROUTINE CGBTRS_64(TRANSA, N, KL, KU, NRHS, A, LDA, IPIVOT,
           B, LDB, INFO)

     CHARACTER * 1 TRANSA
     COMPLEX A(LDA,*), B(LDB,*)
     INTEGER*8 N, KL, KU, NRHS, LDA, LDB, INFO
     INTEGER*8 IPIVOT(*)

  F95 INTERFACE
     SUBROUTINE GBTRS([TRANSA], [N], KL, KU, [NRHS], A, [LDA],
            IPIVOT, B, [LDB], [INFO])

     CHARACTER(LEN=1) :: TRANSA
     COMPLEX, DIMENSION(:,:) :: A, B
     INTEGER :: N, KL, KU, NRHS, LDA, LDB, INFO
     INTEGER, DIMENSION(:) :: IPIVOT

     SUBROUTINE GBTRS_64([TRANSA], [N], KL, KU, [NRHS], A, [LDA],
            IPIVOT, B, [LDB], [INFO])

     CHARACTER(LEN=1) :: TRANSA
     COMPLEX, DIMENSION(:,:) :: A, B
     INTEGER(8) :: N, KL, KU, NRHS, LDA, LDB, INFO
     INTEGER(8), DIMENSION(:) :: IPIVOT

  C INTERFACE
     #include <sunperf.h>

     void cgbtrs(char transa, int n, int kl, int  ku,  int  nrhs,
               complex  *a, int lda, int *ipivot, complex *b, int
               ldb, int *info);
     void cgbtrs_64(char transa, long n, long kl, long  ku,  long
               nrhs,  complex *a, long lda, long *ipivot, complex
               *b, long ldb, long *info);

PURPOSE

     cgbtrs solves a system of linear equations
        A * X = B,  A**T * X = B,  or  A**H * X = B with  a  gen-
     eral  band  matrix  A using the LU factorization computed by
     CGBTRF.

ARGUMENTS

     TRANSA (input)
               Specifies the form of the system of equations.   =
               'N':  A * X = B     (No transpose)
               = 'T':  A**T * X = B  (Transpose)
               = 'C':  A**H * X = B  (Conjugate transpose)

               TRANSA is defaulted to 'N' for F95 INTERFACE.

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

     KL (input)
               The number of subdiagonals within the band  of  A.
               KL >= 0.

     KU (input)
               The number of superdiagonals within the band of A.
               KU >= 0.

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

     A (input) Details of the LU factorization of the band matrix
               A, as computed by CGBTRF.  U is stored as an upper
               triangular band matrix with  KL+KU  superdiagonals
               in  rows  1  to  KL+KU+1, and the multipliers used
               during  the  factorization  are  stored  in   rows
               KL+KU+2 to 2*KL+KU+1.

     LDA (input)
               The leading dimension of  the  array  A.   LDA  >=
               2*KL+KU+1.
     IPIVOT (input)
               The pivot indices; for 1 <= i <= N, row i  of  the
               matrix was interchanged with row IPIVOT(i).

     B (input/output)
               On entry, the right hand side matrix B.  On  exit,
               the 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 ille-
               gal value