table of contents
herk(3) | Library Functions Manual | herk(3) |
NAME¶
herk - {he,sy}rk: Hermitian/symmetric rank-k update
SYNOPSIS¶
Functions¶
subroutine CHERK (uplo, trans, n, k, alpha, a, lda, beta,
c, ldc)
CHERK subroutine CSYRK (uplo, trans, n, k, alpha, a, lda, beta,
c, ldc)
CSYRK subroutine DSYRK (uplo, trans, n, k, alpha, a, lda, beta,
c, ldc)
DSYRK subroutine SSYRK (uplo, trans, n, k, alpha, a, lda, beta,
c, ldc)
SSYRK subroutine ZHERK (uplo, trans, n, k, alpha, a, lda, beta,
c, ldc)
ZHERK subroutine ZSYRK (uplo, trans, n, k, alpha, a, lda, beta,
c, ldc)
ZSYRK
Detailed Description¶
Function Documentation¶
subroutine CHERK (character uplo, character trans, integer n, integer k, real alpha, complex, dimension(lda,*) a, integer lda, real beta, complex, dimension(ldc,*) c, integer ldc)¶
CHERK
Purpose:
!> !> CHERK performs one of the hermitian rank k operations !> !> C := alpha*A*A**H + beta*C, !> !> or !> !> C := alpha*A**H*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. !>
Parameters
!> 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. !>
TRANS
!> TRANS is CHARACTER*1 !> On entry, TRANS specifies the operation to be performed as !> follows: !> !> TRANS = 'N' or 'n' C := alpha*A*A**H + beta*C. !> !> TRANS = 'C' or 'c' C := alpha*A**H*A + beta*C. !>
N
!> N is INTEGER !> On entry, N specifies the order of the matrix C. N must be !> at least zero. !>
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 = 'C' or 'c', K specifies the number of rows of the !> matrix A. K must be at least zero. !>
ALPHA
!> ALPHA is REAL !> On entry, ALPHA specifies the scalar alpha. !>
A
!> A is COMPLEX 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. !>
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 ). !>
BETA
!> BETA is REAL !> On entry, BETA specifies the scalar beta. !>
C
!> C is COMPLEX array, dimension ( LDC, N ) !> Before entry with UPLO = 'U' or 'u', the leading n by n !> upper triangular part of the array C must contain the upper !> triangular part of the hermitian matrix and the strictly !> lower triangular part of C is not referenced. On exit, the !> upper triangular part of the array C is overwritten by the !> upper triangular part of the updated matrix. !> Before entry with UPLO = 'L' or 'l', the leading n by n !> lower triangular part of the array C must contain the lower !> triangular part of the hermitian matrix and the strictly !> upper triangular part of C is not referenced. On exit, the !> lower triangular part of the array C is overwritten by the !> lower triangular part of the updated matrix. !> 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. !>
LDC
!> LDC is INTEGER !> On entry, LDC specifies the first dimension of C as declared !> in the calling (sub) program. LDC must be at least !> max( 1, n ). !>
Author
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Further Details:
!> !> Level 3 Blas routine. !> !> -- Written on 8-February-1989. !> Jack Dongarra, Argonne National Laboratory. !> Iain Duff, AERE Harwell. !> Jeremy Du Croz, Numerical Algorithms Group Ltd. !> Sven Hammarling, Numerical Algorithms Group Ltd. !> !> -- Modified 8-Nov-93 to set C(J,J) to REAL( C(J,J) ) when BETA = 1. !> Ed Anderson, Cray Research Inc. !>
Definition at line 172 of file cherk.f.
subroutine CSYRK (character uplo, character trans, integer n, integer k, complex alpha, complex, dimension(lda,*) a, integer lda, complex beta, complex, dimension(ldc,*) c, integer ldc)¶
CSYRK
Purpose:
!> !> CSYRK 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 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
!> 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. !>
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. !>
N
!> N is INTEGER !> On entry, N specifies the order of the matrix C. N must be !> at least zero. !>
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. !>
ALPHA
!> ALPHA is COMPLEX !> On entry, ALPHA specifies the scalar alpha. !>
A
!> A is COMPLEX 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. !>
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 ). !>
BETA
!> BETA is COMPLEX !> On entry, BETA specifies the scalar beta. !>
C
!> C is COMPLEX array, dimension ( LDC, N ) !> Before entry with UPLO = 'U' or 'u', the leading n by n !> upper triangular part of the array C must contain the upper !> triangular part of the symmetric matrix and the strictly !> lower triangular part of C is not referenced. On exit, the !> upper triangular part of the array C is overwritten by the !> upper triangular part of the updated matrix. !> Before entry with UPLO = 'L' or 'l', the leading n by n !> lower triangular part of the array C must contain the lower !> triangular part of the symmetric matrix and the strictly !> upper triangular part of C is not referenced. On exit, the !> lower triangular part of the array C is overwritten by the !> lower triangular part of the updated matrix. !>
LDC
!> LDC is INTEGER !> On entry, LDC specifies the first dimension of C as declared !> in the calling (sub) program. LDC must be at least !> max( 1, n ). !>
Author
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Further Details:
!> !> Level 3 Blas routine. !> !> -- Written on 8-February-1989. !> Jack Dongarra, Argonne National Laboratory. !> Iain Duff, AERE Harwell. !> Jeremy Du Croz, Numerical Algorithms Group Ltd. !> Sven Hammarling, Numerical Algorithms Group Ltd. !>
Definition at line 166 of file csyrk.f.
subroutine DSYRK (character uplo, character trans, integer n, integer k, double precision alpha, double precision, dimension(lda,*) a, integer lda, double precision beta, double precision, dimension(ldc,*) c, integer ldc)¶
DSYRK
Purpose:
!> !> DSYRK 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 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
!> 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. !>
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. !> !> TRANS = 'C' or 'c' C := alpha*A**T*A + beta*C. !>
N
!> N is INTEGER !> On entry, N specifies the order of the matrix C. N must be !> at least zero. !>
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' or 'C' or 'c', K specifies the number !> of rows of the matrix A. K must be at least zero. !>
ALPHA
!> ALPHA is DOUBLE PRECISION. !> On entry, ALPHA specifies the scalar alpha. !>
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. !>
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 ). !>
BETA
!> BETA is DOUBLE PRECISION. !> On entry, BETA specifies the scalar beta. !>
C
!> C is DOUBLE PRECISION array, dimension ( LDC, N ) !> Before entry with UPLO = 'U' or 'u', the leading n by n !> upper triangular part of the array C must contain the upper !> triangular part of the symmetric matrix and the strictly !> lower triangular part of C is not referenced. On exit, the !> upper triangular part of the array C is overwritten by the !> upper triangular part of the updated matrix. !> Before entry with UPLO = 'L' or 'l', the leading n by n !> lower triangular part of the array C must contain the lower !> triangular part of the symmetric matrix and the strictly !> upper triangular part of C is not referenced. On exit, the !> lower triangular part of the array C is overwritten by the !> lower triangular part of the updated matrix. !>
LDC
!> LDC is INTEGER !> On entry, LDC specifies the first dimension of C as declared !> in the calling (sub) program. LDC must be at least !> max( 1, n ). !>
Author
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Further Details:
!> !> Level 3 Blas routine. !> !> -- Written on 8-February-1989. !> Jack Dongarra, Argonne National Laboratory. !> Iain Duff, AERE Harwell. !> Jeremy Du Croz, Numerical Algorithms Group Ltd. !> Sven Hammarling, Numerical Algorithms Group Ltd. !>
Definition at line 168 of file dsyrk.f.
subroutine SSYRK (character uplo, character trans, integer n, integer k, real alpha, real, dimension(lda,*) a, integer lda, real beta, real, dimension(ldc,*) c, integer ldc)¶
SSYRK
Purpose:
!> !> SSYRK 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 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
!> 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. !>
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. !> !> TRANS = 'C' or 'c' C := alpha*A**T*A + beta*C. !>
N
!> N is INTEGER !> On entry, N specifies the order of the matrix C. N must be !> at least zero. !>
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' or 'C' or 'c', K specifies the number !> of rows of the matrix A. K must be at least zero. !>
ALPHA
!> ALPHA is REAL !> On entry, ALPHA specifies the scalar alpha. !>
A
!> A is REAL 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. !>
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 ). !>
BETA
!> BETA is REAL !> On entry, BETA specifies the scalar beta. !>
C
!> C is REAL array, dimension ( LDC, N ) !> Before entry with UPLO = 'U' or 'u', the leading n by n !> upper triangular part of the array C must contain the upper !> triangular part of the symmetric matrix and the strictly !> lower triangular part of C is not referenced. On exit, the !> upper triangular part of the array C is overwritten by the !> upper triangular part of the updated matrix. !> Before entry with UPLO = 'L' or 'l', the leading n by n !> lower triangular part of the array C must contain the lower !> triangular part of the symmetric matrix and the strictly !> upper triangular part of C is not referenced. On exit, the !> lower triangular part of the array C is overwritten by the !> lower triangular part of the updated matrix. !>
LDC
!> LDC is INTEGER !> On entry, LDC specifies the first dimension of C as declared !> in the calling (sub) program. LDC must be at least !> max( 1, n ). !>
Author
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Further Details:
!> !> Level 3 Blas routine. !> !> -- Written on 8-February-1989. !> Jack Dongarra, Argonne National Laboratory. !> Iain Duff, AERE Harwell. !> Jeremy Du Croz, Numerical Algorithms Group Ltd. !> Sven Hammarling, Numerical Algorithms Group Ltd. !>
Definition at line 168 of file ssyrk.f.
subroutine ZHERK (character uplo, character trans, integer n, integer k, double precision alpha, complex*16, dimension(lda,*) a, integer lda, double precision beta, complex*16, dimension(ldc,*) c, integer ldc)¶
ZHERK
Purpose:
!> !> ZHERK performs one of the hermitian rank k operations !> !> C := alpha*A*A**H + beta*C, !> !> or !> !> C := alpha*A**H*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. !>
Parameters
!> 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. !>
TRANS
!> TRANS is CHARACTER*1 !> On entry, TRANS specifies the operation to be performed as !> follows: !> !> TRANS = 'N' or 'n' C := alpha*A*A**H + beta*C. !> !> TRANS = 'C' or 'c' C := alpha*A**H*A + beta*C. !>
N
!> N is INTEGER !> On entry, N specifies the order of the matrix C. N must be !> at least zero. !>
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 = 'C' or 'c', K specifies the number of rows of the !> matrix A. K must be at least zero. !>
ALPHA
!> ALPHA is DOUBLE PRECISION . !> On entry, ALPHA specifies the scalar alpha. !>
A
!> A is COMPLEX*16 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. !>
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 ). !>
BETA
!> BETA is DOUBLE PRECISION. !> On entry, BETA specifies the scalar beta. !>
C
!> C is COMPLEX*16 array, dimension ( LDC, N ) !> Before entry with UPLO = 'U' or 'u', the leading n by n !> upper triangular part of the array C must contain the upper !> triangular part of the hermitian matrix and the strictly !> lower triangular part of C is not referenced. On exit, the !> upper triangular part of the array C is overwritten by the !> upper triangular part of the updated matrix. !> Before entry with UPLO = 'L' or 'l', the leading n by n !> lower triangular part of the array C must contain the lower !> triangular part of the hermitian matrix and the strictly !> upper triangular part of C is not referenced. On exit, the !> lower triangular part of the array C is overwritten by the !> lower triangular part of the updated matrix. !> 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. !>
LDC
!> LDC is INTEGER !> On entry, LDC specifies the first dimension of C as declared !> in the calling (sub) program. LDC must be at least !> max( 1, n ). !>
Author
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Further Details:
!> !> Level 3 Blas routine. !> !> -- Written on 8-February-1989. !> Jack Dongarra, Argonne National Laboratory. !> Iain Duff, AERE Harwell. !> Jeremy Du Croz, Numerical Algorithms Group Ltd. !> Sven Hammarling, Numerical Algorithms Group Ltd. !> !> -- Modified 8-Nov-93 to set C(J,J) to DBLE( C(J,J) ) when BETA = 1. !> Ed Anderson, Cray Research Inc. !>
Definition at line 172 of file zherk.f.
subroutine ZSYRK (character uplo, character trans, integer n, integer k, complex*16 alpha, complex*16, dimension(lda,*) a, integer lda, complex*16 beta, complex*16, dimension(ldc,*) c, integer ldc)¶
ZSYRK
Purpose:
!> !> ZSYRK 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 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
!> 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. !>
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. !>
N
!> N is INTEGER !> On entry, N specifies the order of the matrix C. N must be !> at least zero. !>
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. !>
ALPHA
!> ALPHA is COMPLEX*16 !> On entry, ALPHA specifies the scalar alpha. !>
A
!> A is COMPLEX*16 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. !>
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 ). !>
BETA
!> BETA is COMPLEX*16 !> On entry, BETA specifies the scalar beta. !>
C
!> C is COMPLEX*16 array, dimension ( LDC, N ) !> Before entry with UPLO = 'U' or 'u', the leading n by n !> upper triangular part of the array C must contain the upper !> triangular part of the symmetric matrix and the strictly !> lower triangular part of C is not referenced. On exit, the !> upper triangular part of the array C is overwritten by the !> upper triangular part of the updated matrix. !> Before entry with UPLO = 'L' or 'l', the leading n by n !> lower triangular part of the array C must contain the lower !> triangular part of the symmetric matrix and the strictly !> upper triangular part of C is not referenced. On exit, the !> lower triangular part of the array C is overwritten by the !> lower triangular part of the updated matrix. !>
LDC
!> LDC is INTEGER !> On entry, LDC specifies the first dimension of C as declared !> in the calling (sub) program. LDC must be at least !> max( 1, n ). !>
Author
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Further Details:
!> !> Level 3 Blas routine. !> !> -- Written on 8-February-1989. !> Jack Dongarra, Argonne National Laboratory. !> Iain Duff, AERE Harwell. !> Jeremy Du Croz, Numerical Algorithms Group Ltd. !> Sven Hammarling, Numerical Algorithms Group Ltd. !>
Definition at line 166 of file zsyrk.f.
Author¶
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