Contents

• NAME
• SYNOPSIS
  • F95 INTERFACE
  • C INTERFACE
• PURPOSE
• ARGUMENTS

NAME

     sspr2 - perform  the  symmetric  rank  2  operation    A  :=
     alpha*x*y' + alpha*y*x' + A

SYNOPSIS

     SUBROUTINE SSPR2(UPLO, N, ALPHA, X, INCX, Y, INCY, AP)

     CHARACTER * 1 UPLO
     INTEGER N, INCX, INCY
     REAL ALPHA
     REAL X(*), Y(*), AP(*)

     SUBROUTINE SSPR2_64(UPLO, N, ALPHA, X, INCX, Y, INCY, AP)

     CHARACTER * 1 UPLO
     INTEGER*8 N, INCX, INCY
     REAL ALPHA
     REAL X(*), Y(*), AP(*)

  F95 INTERFACE
     SUBROUTINE SPR2(UPLO, [N], ALPHA, X, [INCX], Y, [INCY], AP)

     CHARACTER(LEN=1) :: UPLO
     INTEGER :: N, INCX, INCY
     REAL :: ALPHA
     REAL, DIMENSION(:) :: X, Y, AP

     SUBROUTINE SPR2_64(UPLO, [N], ALPHA, X, [INCX], Y, [INCY], AP)

     CHARACTER(LEN=1) :: UPLO
     INTEGER(8) :: N, INCX, INCY
     REAL :: ALPHA
     REAL, DIMENSION(:) :: X, Y, AP

  C INTERFACE
     #include <sunperf.h>

     void sspr2(char uplo, int n,  float  alpha,  float  *x,  int
               incx, float *y, int incy, float *ap);

     void sspr2_64(char uplo, long n, float alpha, float *x, long
               incx, float *y, long incy, float *ap);

PURPOSE

     sspr2  performs  the  symmetric  rank  2  operation   A   :=
     alpha*x*y'  + alpha*y*x' + A, where alpha is a scalar, x and
     y are n element vectors and A is an n by n symmetric matrix,
     supplied in packed form.

ARGUMENTS

     UPLO (input)
               On entry, UPLO  specifies  whether  the  upper  or
               lower  triangular part of the matrix A is supplied
               in the packed array A as follows:

               UPLO = 'U' or 'u'   The upper triangular part of A
               is supplied in AP.

               UPLO = 'L' or 'l'   The lower triangular part of A
               is supplied in AP.

               Unchanged on exit.

     N (input)
               On entry, N specifies the order of the  matrix  A.
               N >= 0.  Unchanged on exit.

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

     X (input)
               Real array, dimension  (1  +  (n  -  1)*abs(INCX))
               Before entry, the incremented array X must contain
               the n element vector x.  Unchanged on exit.

     INCX (input)
               On entry, INCX specifies  the  increment  for  the
               elements of X. INCX <> 0.  Unchanged on exit.

     Y (input)
               Real array, dimension  (1  +  (n  -  1)*abs(INCY))
               Before entry, the incremented array Y must contain
               the n element vector y.  Unchanged on exit.

     INCY (input)
               On entry, INCY specifies  the  increment  for  the
               elements of Y. INCY <> 0.  Unchanged on exit.
     AP (input/output)
               Real array, dimension  ((  n*(n  +  1))/2)  Before
               entry  with   UPLO = 'U' or 'u', the array AP must
               contain the upper triangular part of the symmetric
               matrix  packed  sequentially, column by column, so
               that AP( 1 ) contains a( 1, 1 ), AP( 2 ) and AP( 3
               )  contain  a(  1, 2 ) and a( 2, 2 ) respectively,
               and so on. On exit, the array A is overwritten  by
               the  upper  triangular part of the updated matrix.
               Before entry with UPLO = 'L' or 'l', the array  AP
               must contain the lower triangular part of the sym-
               metric  matrix  packed  sequentially,  column   by
               column,  so that AP( 1 ) contains a( 1, 1 ), AP( 2
               ) and AP( 3 ) contain a( 2, 1 )  and  a(  3,  1  )
               respectively,  and so on. On exit, the array AP is
               overwritten by the lower triangular  part  of  the
               updated matrix.