cgbtrs-f(3)

cgbtrs.f –

Synopsis

Functions/Subroutines

subroutine cgbtrs (TRANS, N, KL, KU, NRHS, AB, LDAB, IPIV, B, LDB, INFO)
CGBTRS

Function/Subroutine Documentation

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

CGBTRS

Purpose:

 CGBTRS solves 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.

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**H * X = B (Conjugate 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 COMPLEX array, dimension (LDAB,N)
 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.

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 COMPLEX 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 cgbtrs.f.

Author

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