# dsfrk.f man page

dsfrk.f —

## Synopsis

### Functions/Subroutines

subroutinedsfrk(TRANSR, UPLO, TRANS, N, K, ALPHA, A, LDA, BETA, C)DSFRKperforms a symmetric rank-k operation for matrix in RFP format.

## Function/Subroutine Documentation

### subroutine dsfrk (characterTRANSR, characterUPLO, characterTRANS, integerN, integerK, double precisionALPHA, double precision, dimension( lda, * )A, integerLDA, double precisionBETA, double precision, dimension( * )C)

**DSFRK** performs a symmetric rank-k operation for matrix in RFP format.

**Purpose:**

```
Level 3 BLAS like routine for C in RFP Format.
DSFRK performs one of the symmetric rank--k operations
C := alpha*A*A**T + beta*C,
or
C := alpha*A**T*A + beta*C,
where alpha and beta are real scalars, C is an n--by--n symmetric
matrix and A is an n--by--k matrix in the first case and a k--by--n
matrix in the second case.
```

**Parameters:**

*TRANSR*

```
TRANSR is CHARACTER*1
= 'N': The Normal Form of RFP A is stored;
= 'T': The Transpose Form of RFP A is stored.
```

*UPLO*

```
UPLO is CHARACTER*1
On entry, UPLO specifies whether the upper or lower
triangular part of the array C is to be referenced as
follows:
UPLO = 'U' or 'u' Only the upper triangular part of C
is to be referenced.
UPLO = 'L' or 'l' Only the lower triangular part of C
is to be referenced.
Unchanged on exit.
```

*TRANS*

```
TRANS is CHARACTER*1
On entry, TRANS specifies the operation to be performed as
follows:
TRANS = 'N' or 'n' C := alpha*A*A**T + beta*C.
TRANS = 'T' or 't' C := alpha*A**T*A + beta*C.
Unchanged on exit.
```

*N*

```
N is INTEGER
On entry, N specifies the order of the matrix C. N must be
at least zero.
Unchanged on exit.
```

*K*

```
K is INTEGER
On entry with TRANS = 'N' or 'n', K specifies the number
of columns of the matrix A, and on entry with TRANS = 'T'
or 't', K specifies the number of rows of the matrix A. K
must be at least zero.
Unchanged on exit.
```

*ALPHA*

```
ALPHA is DOUBLE PRECISION
On entry, ALPHA specifies the scalar alpha.
Unchanged on exit.
```

*A*

```
A is DOUBLE PRECISION array, dimension (LDA,ka)
where KA
is K when TRANS = 'N' or 'n', and is N otherwise. Before
entry with TRANS = 'N' or 'n', the leading N--by--K part of
the array A must contain the matrix A, otherwise the leading
K--by--N part of the array A must contain the matrix A.
Unchanged on exit.
```

*LDA*

```
LDA is INTEGER
On entry, LDA specifies the first dimension of A as declared
in the calling (sub) program. When TRANS = 'N' or 'n'
then LDA must be at least max( 1, n ), otherwise LDA must
be at least max( 1, k ).
Unchanged on exit.
```

*BETA*

```
BETA is DOUBLE PRECISION
On entry, BETA specifies the scalar beta.
Unchanged on exit.
```

*C*

```
C is DOUBLE PRECISION array, dimension (NT)
NT = N*(N+1)/2. On entry, the symmetric matrix C in RFP
Format. RFP Format is described by TRANSR, UPLO and N.
```

**Author:**

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

**Date:**

September 2012

Definition at line 166 of file dsfrk.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

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