- SUBROUTINE SGBTRS(
- TRANS, N, KL, KU, NRHS, AB, LDAB, IPIV, B, LDB, INFO )
- CHARACTER TRANS
- INTEGER INFO, KL, KU, LDAB, LDB, N, NRHS
- INTEGER IPIV( * )
- REAL AB( LDAB, * ), B( LDB, * )
PURPOSESGBTRS solves a system of linear equations
A * X = B or A' * X = B with a general band matrix A using the LU factorization computed by SGBTRF.
- TRANS (input) CHARACTER*1
Specifies the form of the system of equations.
= 'N': A * X = B (No transpose)
= 'T': A'* X = B (Transpose)
= 'C': A'* X = B (Conjugate transpose = Transpose)
- N (input) INTEGER
- The order of the matrix A. N >= 0.
- KL (input) INTEGER
- The number of subdiagonals within the band of A. KL >= 0.
- KU (input) INTEGER
- The number of superdiagonals within the band of A. KU >= 0.
- NRHS (input) INTEGER
- The number of right hand sides, i.e., the number of columns of the matrix B. NRHS >= 0.
- AB (input) REAL array, dimension (LDAB,N)
- Details of the LU factorization of the band matrix A, as computed by SGBTRF. 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.
- LDAB (input) INTEGER
- The leading dimension of the array AB. LDAB >= 2*KL+KU+1.
- IPIV (input) INTEGER array, dimension (N)
- The pivot indices; for 1 <= i <= N, row i of the matrix was interchanged with row IPIV(i).
- B (input/output) REAL array, dimension (LDB,NRHS)
- On entry, the right hand side matrix B. On exit, the solution matrix X.
- LDB (input) INTEGER
- The leading dimension of the array B. LDB >= max(1,N).
- INFO (output) INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value