# zgbtrs (3) - Linux Manuals

zgbtrs.f -

## SYNOPSIS

### Functions/Subroutines

subroutine zgbtrs (TRANS, N, KL, KU, NRHS, AB, LDAB, IPIV, B, LDB, INFO)
ZGBTRS

## Function/Subroutine Documentation

### subroutine zgbtrs (characterTRANS, integerN, integerKL, integerKU, integerNRHS, complex*16, dimension( ldab, * )AB, integerLDAB, integer, dimension( * )IPIV, complex*16, dimension( ldb, * )B, integerLDB, integerINFO)

ZGBTRS

Purpose:

``` ZGBTRS 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 ZGBTRF.
```

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

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

KL

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

KU

```          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

```          AB is COMPLEX*16 array, dimension (LDAB,N)
Details of the LU factorization of the band matrix A, as
computed by ZGBTRF.  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

```          B is COMPLEX*16 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