SSPR2(3)

Hey bestie! 💅 Welcome to the sspr2.f(3) page from the Library Functions Manual. This is the <pink>SSPR2</pink> BLAS routine, and it’s lowkey iconic. Let’s get into it. 🎀

🌸 NAME 🌸

The file this page is named after is exactly:

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/BLAS/SRC/sspr2.f

✨ SYNOPSIS ✨

🧚 Functions/Subroutines 🧚

• subroutine SSPR2 (uplo, n, alpha, x, incx, y, incy, ap) — SSPR2 (yes, that’s the whole vibe)

💖 Function/Subroutine Documentation 💖

subroutine SSPR2 (character uplo, integer n, real alpha, real, dimension(*)
       x, integer incx, real, dimension(*) y, integer incy, real, dimension(*)
       ap)

Subroutine name: SSPR2. This is your main character subroutine, bestie. 💫

🎯 Purpose 🎯

Okay so SSPR2 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 supplied in packed form. That’s the whole bit, no cap. 🦋

🎀 Parameters 🎀

• UPLO — UPLO is CHARACTER*1. On entry, UPLO tells you whether the upper or lower triangular part of matrix A is supplied in packed array AP, like this:
  • 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 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. ⚠️
• 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 👑

These brilliant folks are credited:

• 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 141 of file sspr2.f.

👑 Author 👑

Generated automatically by Doxygen for LAPACK from the source code. 🤖✨

💖 That’s a wrap, bestie! Sign-off: LAPACK Version 3.12.0, source /home/abui...SRC/sspr2.f(3). Go slay those packed symmetric rank 2 updates! 💅🔥