BLAS/SRC/ssyr2.f(3)        Library Functions Manual        BLAS/SRC/ssyr2.f(3)

NAME
       BLAS/SRC/ssyr2.f

SYNOPSIS
   Functions/Subroutines
       subroutine ssyr2 (uplo, n, alpha, x, incx, y, incy, a, lda)
           SSYR2

Function/Subroutine Documentation
   subroutine ssyr2 (character uplo, integer n, real alpha, real, dimension(*)
       x, integer incx, real, dimension(*) y, integer incy, real,
       dimension(lda,*) a, integer lda)
       SSYR2

       Purpose:


            SSYR2  performs the symmetric rank 2 operation

               A := alpha*x*y**T + alpha*y*x**T + A,

            where alpha is a scalar, x and y are n element vectors and A is an n
            by n symmetric matrix.

       Parameters
           UPLO

                     UPLO is CHARACTER*1
                      On entry, UPLO specifies whether the upper or lower
                      triangular part of the array A is to be referenced as
                      follows:

                         UPLO = 'U' or 'u'   Only the upper triangular part of A
                                             is to be referenced.

                         UPLO = 'L' or 'l'   Only the lower triangular part of A
                                             is to be referenced.

           N

                     N is INTEGER
                      On entry, N specifies the order of the matrix A.
                      N must be at least zero.

           ALPHA

                     ALPHA is REAL
                      On entry, ALPHA specifies the scalar alpha.

           X

                     X is REAL array, dimension at least
                      ( 1 + ( n - 1 )*abs( INCX ) ).
                      Before entry, the incremented array X must contain the n
                      element vector x.

           INCX

                     INCX is INTEGER
                      On entry, INCX specifies the increment for the elements of
                      X. INCX must not be zero.

           Y

                     Y is REAL array, dimension at least
                      ( 1 + ( n - 1 )*abs( INCY ) ).
                      Before entry, the incremented array Y must contain the n
                      element vector y.

           INCY

                     INCY is INTEGER
                      On entry, INCY specifies the increment for the elements of
                      Y. INCY must not be zero.

           A

                     A is REAL array, dimension ( LDA, N )
                      Before entry with  UPLO = 'U' or 'u', the leading n by n
                      upper triangular part of the array A must contain the upper
                      triangular part of the symmetric matrix and the strictly
                      lower triangular part of A is not referenced. On exit, the
                      upper triangular part of the array A 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 A must contain the lower
                      triangular part of the symmetric matrix and the strictly
                      upper triangular part of A is not referenced. On exit, the
                      lower triangular part of the array A is overwritten by the
                      lower triangular part of the updated matrix.

           LDA

                     LDA is INTEGER
                      On entry, LDA specifies the first dimension of A as declared
                      in the calling (sub) program. LDA must be at least
                      max( 1, n ).

       Author
           Univ. of Tennessee

           Univ. of California Berkeley

           Univ. of Colorado Denver

           NAG Ltd.

       Further Details:


             Level 2 Blas routine.

             -- Written on 22-October-1986.
                Jack Dongarra, Argonne National Lab.
                Jeremy Du Croz, Nag Central Office.
                Sven Hammarling, Nag Central Office.
                Richard Hanson, Sandia National Labs.

       Definition at line 146 of file ssyr2.f.

Author
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LAPACK                          Version 3.12.0             BLAS/SRC/ssyr2.f(3)