SLAGS2(3)

🦋 SLAGS2(3) 🦋

okay so bestie, this page is for SLAGS2(3) — manual-name situation: slags2.f(3) / Library Functions Manual, header path /home/abui...RC/slags2.f(3). The actual source file is the whole NAME vibe below, and yes we're keeping every crumb. 💖

🎀 NAME 🎀

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/SRC/slags2.f

✨ SYNOPSIS ✨

Under Functions/Subroutines, we have this icon:

subroutine SLAGS2 (upper, a1, a2, a3, b1, b2, b3, csu, snu, csv, snv,
           csq, snq)
           SLAGS2 computes 2-by-2 orthogonal matrices U, V, and Q, and applies
           them to matrices A and B such that the rows of the transformed A and
           B are parallel.

🌸 Function/Subroutine Documentation 🌸

The signature is literally this, no cap:

subroutine SLAGS2 (logical upper, real a1, real a2, real a3, real b1, real
    b2, real b3, real csu, real snu, real csv, real snv, real csq, real snq)

SLAGS2 computes 2-by-2 orthogonal matrices U, V, and Q, and applies them to matrices A and B so that the rows of the transformed A and B are parallel. ✨

💅 Purpose 💅

okay so the actual purpose block is giving matrix math main-character energy, and I'm putting it here exactly so nothing gets lost:

!>
!> SLAGS2 computes 2-by-2 orthogonal matrices U, V and Q, such
!> that if ( UPPER ) then
!>
!>           U**T *A*Q = U**T *( A1 A2 )*Q = ( x  0  )
!>                             ( 0  A3 )     ( x  x  )
!> and
!>           V**T*B*Q = V**T *( B1 B2 )*Q = ( x  0  )
!>                            ( 0  B3 )     ( x  x  )
!>
!> or if ( .NOT.UPPER ) then
!>
!>           U**T *A*Q = U**T *( A1 0  )*Q = ( x  x  )
!>                             ( A2 A3 )     ( 0  x  )
!> and
!>           V**T*B*Q = V**T*( B1 0  )*Q = ( x  x  )
!>                           ( B2 B3 )     ( 0  x  )
!>
!> The rows of the transformed A and B are parallel, where
!>
!>   U = (  CSU  SNU ), V = (  CSV SNV ), Q = (  CSQ   SNQ )
!>       ( -SNU  CSU )      ( -SNV CSV )      ( -SNQ   CSQ )
!>
!> Z**T denotes the transpose of Z.
!>
!>

🫶 Parameters 🫶

• UPPER — is LOGICAL; = .TRUE. means the input matrices A and B are upper triangular, and = .FALSE. means the input matrices A and B are lower triangular. 💅
• A1 — is REAL.
• A2 — is REAL.
• A3 — is REAL; on entry, A1, A2 and A3 are elements of the input 2-by-2 upper (lower) triangular matrix A. 🦋
• B1 — is REAL.
• B2 — is REAL.
• B3 — is REAL; on entry, B1, B2 and B3 are elements of the input 2-by-2 upper (lower) triangular matrix B. 🌸
• CSU — is REAL.
• SNU — is REAL; the desired orthogonal matrix U. 👑
• CSV — is REAL.
• SNV — is REAL; the desired orthogonal matrix V. ✨
• CSQ — is REAL.
• SNQ — is REAL; the desired orthogonal matrix Q. 💖

👑 Author 👑

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

Definition at line 150 of file slags2.f.

🧚 Author 🧚

Generated automatically by Doxygen for LAPACK from the source code.

---

💖 That's the whole page, bestie — LAPACK Version 3.12.0, footer path /home/abui...RC/slags2.f(3), and we're out. 🫶✨