---
name: "csyconvf.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/csyconvf.f"
---

# csyconvf.f(3)

## NAME

SRC/csyconvf.f

## SYNOPSIS

### Functions/Subroutines

subroutine **csyconvf** (uplo, way, n, a, lda, e, ipiv, info)\
 **CSYCONVF**

## Function/Subroutine Documentation

### subroutine csyconvf (character uplo, character way, integer n, complex, dimension( lda, \* ) a, integer lda, complex, dimension( \* ) e, integer, dimension( \* ) ipiv, integer info)

**CSYCONVF**

**Purpose:**

```
!> If parameter WAY = 'C':
!> CSYCONVF converts the factorization output format used in
!> CSYTRF provided on entry in parameter A into the factorization
!> output format used in CSYTRF_RK (or CSYTRF_BK) that is stored
!> on exit in parameters A and E. It also converts in place details of
!> the interchanges stored in IPIV from the format used in CSYTRF into
!> the format used in CSYTRF_RK (or CSYTRF_BK).
!>
!> If parameter WAY = 'R':
!> CSYCONVF performs the conversion in reverse direction, i.e.
!> converts the factorization output format used in CSYTRF_RK
!> (or CSYTRF_BK) provided on entry in parameters A and E into
!> the factorization output format used in CSYTRF that is stored
!> on exit in parameter A. It also converts in place details of
!> the interchanges stored in IPIV from the format used in CSYTRF_RK
!> (or CSYTRF_BK) into the format used in CSYTRF.
!>
!> CSYCONVF can also convert in Hermitian matrix case, i.e. between
!> formats used in CHETRF and CHETRF_RK (or CHETRF_BK).
!>
```

**Parameters**

*UPLO*

```
!>          UPLO is CHARACTER*1
!>          Specifies whether the details of the factorization are
!>          stored as an upper or lower triangular matrix A.
!>          = 'U':  Upper triangular
!>          = 'L':  Lower triangular
!>
```

*WAY*

```
!>          WAY is CHARACTER*1
!>          = 'C': Convert
!>          = 'R': Revert
!>
```

*N*

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

*A*

```
!>          A is COMPLEX array, dimension (LDA,N)
!>
!>          1) If WAY ='C':
!>
!>          On entry, contains factorization details in format used in
!>          CSYTRF:
!>            a) all elements of the symmetric block diagonal
!>               matrix D on the diagonal of A and on superdiagonal
!>               (or subdiagonal) of A, and
!>            b) If UPLO = 'U': multipliers used to obtain factor U
!>               in the superdiagonal part of A.
!>               If UPLO = 'L': multipliers used to obtain factor L
!>               in the superdiagonal part of A.
!>
!>          On exit, contains factorization details in format used in
!>          CSYTRF_RK or CSYTRF_BK:
!>            a) ONLY diagonal elements of the symmetric block diagonal
!>               matrix D on the diagonal of A, i.e. D(k,k) = A(k,k);
!>               (superdiagonal (or subdiagonal) elements of D
!>                are stored on exit in array E), and
!>            b) If UPLO = 'U': factor U in the superdiagonal part of A.
!>               If UPLO = 'L': factor L in the subdiagonal part of A.
!>
!>          2) If WAY = 'R':
!>
!>          On entry, contains factorization details in format used in
!>          CSYTRF_RK or CSYTRF_BK:
!>            a) ONLY diagonal elements of the symmetric block diagonal
!>               matrix D on the diagonal of A, i.e. D(k,k) = A(k,k);
!>               (superdiagonal (or subdiagonal) elements of D
!>                are stored on exit in array E), and
!>            b) If UPLO = 'U': factor U in the superdiagonal part of A.
!>               If UPLO = 'L': factor L in the subdiagonal part of A.
!>
!>          On exit, contains factorization details in format used in
!>          CSYTRF:
!>            a) all elements of the symmetric block diagonal
!>               matrix D on the diagonal of A and on superdiagonal
!>               (or subdiagonal) of A, and
!>            b) If UPLO = 'U': multipliers used to obtain factor U
!>               in the superdiagonal part of A.
!>               If UPLO = 'L': multipliers used to obtain factor L
!>               in the superdiagonal part of A.
!>
```

*LDA*

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

*E*

```
!>          E is COMPLEX array, dimension (N)
!>
!>          1) If WAY ='C':
!>
!>          On entry, just a workspace.
!>
!>          On exit, contains the superdiagonal (or subdiagonal)
!>          elements of the symmetric block diagonal matrix D
!>          with 1-by-1 or 2-by-2 diagonal blocks, where
!>          If UPLO = 'U': E(i) = D(i-1,i), i=2:N, E(1) is set to 0;
!>          If UPLO = 'L': E(i) = D(i+1,i), i=1:N-1, E(N) is set to 0.
!>
!>          2) If WAY = 'R':
!>
!>          On entry, contains the superdiagonal (or subdiagonal)
!>          elements of the symmetric block diagonal matrix D
!>          with 1-by-1 or 2-by-2 diagonal blocks, where
!>          If UPLO = 'U': E(i) = D(i-1,i),i=2:N, E(1) not referenced;
!>          If UPLO = 'L': E(i) = D(i+1,i),i=1:N-1, E(N) not referenced.
!>
!>          On exit, is not changed
!>
```

*IPIV*

```
!>          IPIV is INTEGER array, dimension (N)
!>
!>          1) If WAY ='C':
!>          On entry, details of the interchanges and the block
!>          structure of D in the format used in CSYTRF.
!>          On exit, details of the interchanges and the block
!>          structure of D in the format used in CSYTRF_RK
!>          ( or CSYTRF_BK).
!>
!>          1) If WAY ='R':
!>          On entry, details of the interchanges and the block
!>          structure of D in the format used in CSYTRF_RK
!>          ( or CSYTRF_BK).
!>          On exit, details of the interchanges and the block
!>          structure of D in the format used in CSYTRF.
!>
```

*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.

**Contributors:**

```
!>
!>  November 2017,  Igor Kozachenko,
!>                  Computer Science Division,
!>                  University of California, Berkeley
!>
!>
```

Definition at line **208** of file **csyconvf.f**.

## Author

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