SSYR2(3)

📦 version 3.12.0, in opensuse-leap 16.0

💅 SSYR2 (3) — the ssyr2.f(3) page, bestie edition ✨

okay so this whole thing lives in the Library Functions Manual, and honestly? it's giving legendary BLAS energy. it's the ssyr2.f(3) page, straight out of /home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/BLAS/SRC/ssyr2.f 🎀 no cap, that's literally the path.

🌸 NAME 🌸

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/BLAS/SRC/ssyr2.f

that's the file, that's the name, we move. 💅

✨ SYNOPSIS ✨

Functions/Subroutines

subroutine SSYR2 (uplo, n, alpha, x, incx, y, incy, a, lda)
    SSYR2

like, that's the whole vibe in one line 🫶

🦋 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 — say it with me, main character energy 👑

🎀 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. !>

so yeah — alpha is a scalar, x and y are n element vectors, and A is an n by n symmetric matrix. she takes that whole expression and drops it right back into A. iconic. ✨

🌈 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.

on entry, bestie picks a side: 'U' or 'u' means only the upper triangular part of A gets referenced, and 'L' or 'l' means only the lower triangular part gets referenced. vibe check on the triangle, periodt. 💅

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

N is the order of A, and it must be at least zero. zero is allowed, negative is not the move. 🚫

  • ALPHA
!>          ALPHA is REAL
!>           On entry, ALPHA specifies the scalar alpha.

it's the scalar alpha. that's her job. 🍓

  • 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.

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.

the increment for the elements of X. must not be zero — like, hard no. zero is not invited to this party. 💀

  • 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.

dimension at least ( 1 + ( n - 1 )*abs( INCY ) ) — before entry, the incremented array Y must contain the n element vector y. twin of X, lowkey. 🫶

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

the increment for the elements of Y, and again: 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.

dimension ( LDA, N ). let's break it down, bestie:

  • with UPLO = 'U' or 'u': the leading n by n upper triangular part of A must contain the upper triangular part of the symmetric matrix, and the strictly lower triangular part of A is not referenced. on exit, that upper triangular part is overwritten by the upper triangular part of the updated matrix. ✨
  • with UPLO = 'L' or 'l': the leading n by n lower triangular part of A must contain the lower triangular part of the symmetric matrix, and the strictly upper triangular part of A is not referenced. on exit, that lower triangular part is overwritten by the lower triangular part of the updated matrix. ✨

the other half of A is literally just sitting there unbothered. not referenced. she doesn't need it. 💅

  • 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 ).

the first dimension of A as declared in the calling (sub) program, and it must be at least max( 1, n ). respect the bound. 👑

👑 Author 👑

  • Univ. of Tennessee
  • Univ. of California Berkeley
  • Univ. of Colorado Denver
  • NAG Ltd.

the whole squad, credited. 🫶

💜 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. !>

it's a Level 2 BLAS routine, written on 22-October-1986 by Jack Dongarra (Argonne National Lab), Jeremy Du Croz (Nag Central Office), Sven Hammarling (Nag Central Office) and Richard Hanson (Sandia National Labs). vintage. iconic. still slaying. 🔥

🧚 Definition 🧚

definition at line 146 of file ssyr2.f.

okay that's the whole page!! and for the cute sign-off: this little beauty was generated automatically by Doxygen for LAPACK from the source code, and it's LAPACK Version 3.12.0, tagged <italic>/home/abui...SRC/ssyr2.f(3)</italic> — mwah, bye bestie 💖🎀🦋

📦 where this page comes from