---
name: "slavsp.f"
section: "3"
platform: "linux"
package: "lapack-doc"
version: "3.12.1-2"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/slavsp.f"
---

# slavsp.f(3)

## NAME

TESTING/LIN/slavsp.f

## SYNOPSIS

### Functions/Subroutines

subroutine **slavsp** (uplo, trans, diag, n, nrhs, a, ipiv, b, ldb, info)\
 **SLAVSP**

## Function/Subroutine Documentation

### subroutine slavsp (character uplo, character trans, character diag, integer n, integer nrhs, real, dimension( \* ) a, integer, dimension( \* ) ipiv, real, dimension( ldb, \* ) b, integer ldb, integer info)

**SLAVSP**

**Purpose:**

```
!>
!> SLAVSP  performs one of the matrix-vector operations
!>    x := A*x  or  x := A'*x,
!> where x is an N element vector and  A is one of the factors
!> from the block U*D*U' or L*D*L' factorization computed by SSPTRF.
!>
!> If TRANS = 'N', multiplies by U  or U * D  (or L  or L * D)
!> If TRANS = 'T', multiplies by U' or D * U' (or L' or D * L' )
!> If TRANS = 'C', multiplies by U' or D * U' (or L' or D * L' )
!>
```

**Parameters**

*UPLO*

```
!>          UPLO is CHARACTER*1
!>          Specifies whether the factor stored in A is upper or lower
!>          triangular.
!>          = 'U':  Upper triangular
!>          = 'L':  Lower triangular
!>
```

*TRANS*

```
!>          TRANS is CHARACTER*1
!>          Specifies the operation to be performed:
!>          = 'N':  x := A*x
!>          = 'T':  x := A'*x
!>          = 'C':  x := A'*x
!>
```

*DIAG*

```
!>          DIAG is CHARACTER*1
!>          Specifies whether or not the diagonal blocks are unit
!>          matrices.  If the diagonal blocks are assumed to be unit,
!>          then A = U or A = L, otherwise A = U*D or A = L*D.
!>          = 'U':  Diagonal blocks are assumed to be unit matrices.
!>          = 'N':  Diagonal blocks are assumed to be non-unit matrices.
!>
```

*N*

```
!>          N is INTEGER
!>          The number of rows and columns of the matrix A.  N >= 0.
!>
```

*NRHS*

```
!>          NRHS is INTEGER
!>          The number of right hand sides, i.e., the number of vectors
!>          x to be multiplied by A.  NRHS >= 0.
!>
```

*A*

```
!>          A is REAL array, dimension (N*(N+1)/2)
!>          The block diagonal matrix D and the multipliers used to
!>          obtain the factor U or L, stored as a packed triangular
!>          matrix as computed by SSPTRF.
!>
```

*IPIV*

```
!>          IPIV is INTEGER array, dimension (N)
!>          The pivot indices from SSPTRF.
!>
```

*B*

```
!>          B is REAL array, dimension (LDB,NRHS)
!>          On entry, B contains NRHS vectors of length N.
!>          On exit, B is overwritten with the product A * B.
!>
```

*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 = -k, the k-th argument had an illegal value
!>
```

**Author**

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line **128** of file **slavsp.f**.

## Author

Generated automatically by Doxygen for LAPACK from the source code.