# csyconv.f

Section: LAPACK (3)
Updated: Tue Nov 14 2017
Page Index

csyconv.f

## SYNOPSIS

### Functions/Subroutines

subroutine csyconv (UPLO, WAY, N, A, LDA, IPIV, E, INFO)
CSYCONV

## Function/Subroutine Documentation

### subroutine csyconv (character UPLO, character WAY, integer N, complex, dimension( lda, * ) A, integer LDA, integer, dimension( * ) IPIV, complex, dimension( * ) E, integer INFO)

CSYCONV

Purpose:

``` CSYCONV convert A given by TRF into L and D and vice-versa.
Get Non-diag elements of D (returned in workspace) and
apply or reverse permutation done in TRF.
```

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*D*U**T;
= 'L':  Lower triangular, form is A = L*D*L**T.
```

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)
The block diagonal matrix D and the multipliers used to
obtain the factor U or L as computed by CSYTRF.
```

LDA

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

IPIV

```          IPIV is INTEGER array, dimension (N)
Details of the interchanges and the block structure of D
as determined by CSYTRF.
```

E

```          E is COMPLEX array, dimension (N)
E stores the supdiagonal/subdiagonal of the symmetric 1-by-1
or 2-by-2 block diagonal matrix D in LDLT.
```

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