---
name: "chfrk"
section: "3lapack"
platform: "linux"
package: "liblapack-doc"
version: "3.2.1-8"
release: "Debian 6.0 (Squeeze)"
platforms: ["linux"]
url: "https://new.carta.tech/chfrk/3lapack"
---

# chfrk(3lapack)

3 BLAS like routine for C in RFP Format

## NAME

CHFRK - 3 BLAS like routine for C in RFP Format

## SYNOPSIS

- SUBROUTINE CHFRK(

  TRANSR, UPLO, TRANS, N, K, ALPHA, A, LDA, BETA,

- \+

  C )

- REAL

  ALPHA, BETA

- INTEGER

  K, LDA, N

- CHARACTER

  TRANS, TRANSR, UPLO

- COMPLEX

  A( LDA, \* ), C( \* )

## PURPOSE

Level 3 BLAS like routine for C in RFP Format. CHFRK performs one of the Hermitian rank--k operations\
\
    C := alpha\*A\*conjg( A' ) + beta\*C,\
 or\
\
    C := alpha\*conjg( A' )\*A + beta\*C,\
 where alpha and beta are real scalars, C is an n--by--n Hermitian matrix and A is an n--by--k matrix in the first case and a k--by--n matrix in the second case.\

## ARGUMENTS

TRANSR - (input) CHARACTER. = 'N':  The Normal Form of RFP A is stored;\
 \= 'C':  The Conjugate-transpose Form of RFP A is stored.

- UPLO - (input) CHARACTER.

  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 - (input) CHARACTER.

  On entry,  TRANS  specifies the operation to be performed as follows: TRANS = 'N' or 'n'   C := alpha\*A\*conjg( A' ) + beta\*C. TRANS = 'C' or 'c'   C := alpha\*conjg( A' )\*A + beta\*C. Unchanged on exit.

- N - (input) INTEGER.

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

- K - (input) INTEGER.

  On entry with  TRANS = 'N' or 'n',  K  specifies  the number of  columns   of  the   matrix   A,   and  on   entry   with TRANS = 'C' or 'c',  K  specifies  the number of rows of the matrix A.  K must be at least zero. Unchanged on exit.

- ALPHA - (input) REAL.

  On entry, ALPHA specifies the scalar alpha. Unchanged on exit.

- A - (input) COMPLEX array of 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 - (input) 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 - (input) REAL.

  On entry, BETA specifies the scalar beta. Unchanged on exit.

- C - (input/output) COMPLEX array, dimension ( N\*(N+1)/2 ).

  On entry, the matrix A in RFP Format. RFP Format is described by TRANSR, UPLO and N. Note that the imaginary parts of the diagonal elements need not be set, they are assumed to be zero, and on exit they are set to zero.

## ARGUMENTS