# sgbtrs.f man page

sgbtrs.f —

## Synopsis

### Functions/Subroutines

subroutinesgbtrs(TRANS, N, KL, KU, NRHS, AB, LDAB, IPIV, B, LDB, INFO)SGBTRS

## Function/Subroutine Documentation

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

**SGBTRS**

**Purpose:**

```
SGBTRS 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 SGBTRF.
```

**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*

```
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 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*

```
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 REAL 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 sgbtrs.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

sgbtrs(3) is an alias of sgbtrs.f(3).