BLAS/SRC/sspr.f(3)

💖 BLAS/SRC/sspr.f(3) — Library Functions Manual 💖

okay bestie, welcome to the BLAS/SRC/sspr.f(3) page, aka the Library Functions Manual corner of the group chat. We’re about to vibe with sspr, a Level 2 Blas routine that does a symmetric rank 1 update. It’s giving packed-matrix excellence, no cap. ✨

🌸 NAME 🌸

BLAS/SRC/sspr.f — literally the file/name, and that’s the whole NAME section. Minimalist queen. 💅

✨ SYNOPSIS ✨

🧚 Functions/Subroutines 🧚

       subroutine sspr (uplo, n, alpha, x, incx, ap)
           SSPR

🦋 Function/Subroutine Documentation 🦋

   subroutine sspr (character uplo, integer n, real alpha, real, dimension(*)
       x, integer incx, real, dimension(*) ap)
       SSPR

🎀 Purpose: 🎀

Bestie, SSPR performs the symmetric rank 1 operation:

           !>
           !> SSPR    performs the symmetric rank 1 operation
           !>
           !>    A := alpha*x*x**T + A,
           !>
           !> where alpha is a real scalar, x is an n element vector and A is an
           !> n by n symmetric matrix, supplied in packed form.
           !>

So yes: alpha is a real scalar, x is an n element vector, and A is an n by n symmetric matrix supplied in packed form. Obsessed with a packed queen. 💖

🍓 Parameters 🍓

• UPLO — UPLO is CHARACTER*1. On entry, UPLO specifies whether the upper or lower triangular part of the matrix A is supplied in the packed array AP 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.
• 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.
• AP — AP is REAL array, dimension at least ( ( 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 AP 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 symmetric 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.

🌈 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 126 of file sspr.f.

👑 Author 👑

Generated automatically by Doxygen for LAPACK from the source code.

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xoxo, signing off from LAPACK Version 3.12.0 and the page BLAS/SRC/sspr.f(3); the routine itself was written on 22-October-1986. Stay packed and slay. 💖✨