BLAS/SRC/ssyr2k.f(3)       Library Functions Manual       BLAS/SRC/ssyr2k.f(3)

NAME
       BLAS/SRC/ssyr2k.f

SYNOPSIS
   Functions/Subroutines
       subroutine ssyr2k (uplo, trans, n, k, alpha, a, lda, b, ldb, beta, c,
           ldc)
           SSYR2K

Function/Subroutine Documentation
   subroutine ssyr2k (character uplo, character trans, integer n, integer k,
       real alpha, real, dimension(lda,*) a, integer lda, real,
       dimension(ldb,*) b, integer ldb, real beta, real, dimension(ldc,*) c,
       integer ldc)
       SSYR2K

       Purpose:


           !>
           !> SSYR2K  performs one of the symmetric rank 2k operations
           !>
           !>    C := alpha*A*B**T + alpha*B*A**T + beta*C,
           !>
           !> or
           !>
           !>    C := alpha*A**T*B + alpha*B**T*A + beta*C,
           !>
           !> where  alpha and beta  are scalars, C is an  n by n  symmetric matrix
           !> and  A and B  are  n by k  matrices  in the  first  case  and  k by n
           !> matrices in the second case.
           !>

       Parameters
           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.
           !>

           TRANS

           !>          TRANS is CHARACTER*1
           !>           On entry,  TRANS  specifies the operation to be performed as
           !>           follows:
           !>
           !>              TRANS = 'N' or 'n'   C := alpha*A*B**T + alpha*B*A**T +
           !>                                        beta*C.
           !>
           !>              TRANS = 'T' or 't'   C := alpha*A**T*B + alpha*B**T*A +
           !>                                        beta*C.
           !>
           !>              TRANS = 'C' or 'c'   C := alpha*A**T*B + alpha*B**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  matrices  A and B,  and on  entry  with
           !>           TRANS = 'T' or 't' or 'C' or 'c',  K  specifies  the  number
           !>           of rows of the matrices  A and B.  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 ).
           !>

           B

           !>          B is REAL array, dimension ( LDB, kb ), where kb 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  B  must contain the matrix  B,  otherwise
           !>           the leading  k by n  part of the array  B  must contain  the
           !>           matrix B.
           !>

           LDB

           !>          LDB is INTEGER
           !>           On entry, LDB specifies the first dimension of B as declared
           !>           in  the  calling  (sub)  program.   When  TRANS = 'N' or 'n'
           !>           then  LDB must be at least  max( 1, n ), otherwise  LDB 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 Tennessee


           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 191 of file ssyr2k.f.

Author
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LAPACK                          Version 3.12.0            BLAS/SRC/ssyr2k.f(3)