---
name: "csytrs_aa_2stage"
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/csytrs_aa_2stage.f"
---

# csytrs\_aa\_2stage(3)

Part of [csytrs\_aa\_2stage.f(3)](/csytrs_aa_2stage.f/3.md).

## NAME

SRC/csytrs\_aa\_2stage.f

## SYNOPSIS

### Functions/Subroutines

subroutine **csytrs\_aa\_2stage** (uplo, n, nrhs, a, lda, tb, ltb, ipiv, ipiv2, b, ldb, info)\
 **CSYTRS\_AA\_2STAGE**

## Function/Subroutine Documentation

### subroutine csytrs\_aa\_2stage (character uplo, integer n, integer nrhs, complex, dimension( lda, \* ) a, integer lda, complex, dimension( \* ) tb, integer ltb, integer, dimension( \* ) ipiv, integer, dimension( \* ) ipiv2, complex, dimension( ldb, \* ) b, integer ldb, integer info)

**CSYTRS\_AA\_2STAGE**

**Purpose:**

```
!>
!> CSYTRS_AA_2STAGE solves a system of linear equations A*X = B with a complex
!> symmetric matrix A using the factorization A = U**T*T*U or
!> A = L*T*L**T computed by CSYTRF_AA_2STAGE.
!>
```

**Parameters**

*UPLO*

```
!>          UPLO is CHARACTER*1
!>          Specifies whether the details of the factorization are stored
!>          as an upper or lower triangular matrix.
!>          = 'U':  Upper triangular, form is A = U**T*T*U;
!>          = 'L':  Lower triangular, form is A = L*T*L**T.
!>
```

*N*

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

*NRHS*

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

*A*

```
!>          A is COMPLEX array, dimension (LDA,N)
!>          Details of factors computed by CSYTRF_AA_2STAGE.
!>
```

*LDA*

```
!>          LDA is INTEGER
!>          The leading dimension of the array A.  LDA >= max(1,N).
!>
```

*TB*

```
!>          TB is COMPLEX array, dimension (LTB)
!>          Details of factors computed by CSYTRF_AA_2STAGE.
!>
```

*LTB*

```
!>          LTB is INTEGER
!>          The size of the array TB. LTB >= 4*N.
!>
```

*IPIV*

```
!>          IPIV is INTEGER array, dimension (N)
!>          Details of the interchanges as computed by
!>          CSYTRF_AA_2STAGE.
!>
```

*IPIV2*

```
!>          IPIV2 is INTEGER array, dimension (N)
!>          Details of the interchanges as computed by
!>          CSYTRF_AA_2STAGE.
!>
```

*B*

```
!>          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.

Definition at line **137** of file **csytrs\_aa\_2stage.f**.

## Author

Generated automatically by Doxygen for LAPACK from the source code.