dgbtrs-f(3)

dgbtrs.f –

Synopsis

Functions/Subroutines

subroutine dgbtrs (TRANS, N, KL, KU, NRHS, AB, LDAB, IPIV, B, LDB, INFO)
DGBTRS

Function/Subroutine Documentation

subroutine dgbtrs (characterTRANS, integerN, integerKL, integerKU, integerNRHS, double precision, dimension( ldab, * )AB, integerLDAB, integer, dimension( * )IPIV, double precision, dimension( ldb, * )B, integerLDB, integerINFO)

DGBTRS

Purpose:

 DGBTRS solves a system of linear equations
 A * X = B or A**T * X = B
 with a general band matrix A using the LU factorization computed
 by DGBTRF.

Parameters:

TRANS

 TRANS is CHARACTER*1
 Specifies the form of the system of equations.
 = 'N': A * X = B (No transpose)
 = 'T': A**T* X = B (Transpose)
 = 'C': A**T* X = B (Conjugate transpose = Transpose)

 N is INTEGER
 The order of the matrix A. N >= 0.

 KL is INTEGER
 The number of subdiagonals within the band of A. KL >= 0.

 KU is INTEGER
 The number of superdiagonals within the band of A. KU >= 0.

NRHS

 NRHS is INTEGER
 The number of right hand sides, i.e., the number of columns
 of the matrix B. NRHS >= 0.

 AB is DOUBLE PRECISION array, dimension (LDAB,N)
 Details of the LU factorization of the band matrix A, as
 computed by DGBTRF. 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

 LDAB is INTEGER
 The leading dimension of the array AB. LDAB >= 2*KL+KU+1.

IPIV

 IPIV is INTEGER array, dimension (N)
 The pivot indices; for 1 <= i <= N, row i of the matrix was
 interchanged with row IPIV(i).

 B is DOUBLE PRECISION array, dimension (LDB,NRHS)
 On entry, the right hand side matrix B.
 On exit, the solution matrix X.

LDB

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

INFO

 INFO is INTEGER
 = 0: successful exit
 < 0: if INFO = -i, the i-th argument had an illegal value

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

November 2011

Definition at line 138 of file dgbtrs.f.

Author

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