SLA_SYRPVGRW(3)

💅 SLA_SYRPVGRW(3) 💅

okay so bestie, welcome to the Library Functions Manual page for SLA_SYRPVGRW. The header is giving sla_syrpvgrw.f(3) and also /home/abui..._syrpvgrw.f(3) on repeat — we love a dramatic entrance. This is the LAPACK function that computes the reciprocal pivot growth factor norm(A)/norm(U) for a symmetric indefinite matrix. It's giving linear algebra main character energy, fr fr. 💜

---

💖 NAME 💖

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

That's the file, periodt. No cap. 💅

✨ SYNOPSIS ✨

🧚 Functions/Subroutines 🧚

• real function SLA_SYRPVGRW (uplo, n, info, a, lda, af, ldaf, ipiv, work) — SLA_SYRPVGRW computes the reciprocal pivot growth factor norm(A)/norm(U) for a symmetric indefinite matrix.

🫶 Function/Subroutine Documentation 🫶

real function SLA_SYRPVGRW (character*1 uplo, integer n, integer info, real, dimension( lda, * ) a, integer lda, real, dimension( ldaf, * ) af, integer ldaf, integer, dimension( * ) ipiv, real, dimension( * ) work)

SLA_SYRPVGRW computes the reciprocal pivot growth factor norm(A)/norm(U) for a symmetric indefinite matrix.

🎯 Purpose 🎯

ok so the whole point: SLA_SYRPVGRW computes the reciprocal pivot growth factor norm(A)/norm(U). The source literally says The norm is used. — double space and all, bestie, we're not fixing it. If this is much less than 1, the stability of the LU factorization of the (equilibrated) matrix A could be poor. That also means the solution X, estimated condition numbers, and error bounds could be unreliable. Not dramatic, just facts. 😭

bestie, lowkey pay attention to that: if the factor is much less than 1, things can get shaky fr fr.

🌸 Parameters 🌸

🦋 UPLO 🦋

• UPLO is CHARACTER*1
  • = 'U': Upper triangle of A is stored;
  • = 'L': Lower triangle of A is stored.

🦋 N 🦋

• N is INTEGER
• The number of linear equations, i.e., the order of the matrix A. N >= 0.

🦋 INFO 🦋

• INFO is INTEGER
• The value of INFO returned from SSYTRF, .i.e., the pivot in column INFO is exactly 0.

🦋 A 🦋

• A is REAL array, dimension (LDA,N)
• On entry, the N-by-N matrix A.

🦋 LDA 🦋

• LDA is INTEGER
• The leading dimension of the array A. LDA >= max(1,N).

🦋 AF 🦋

• AF is REAL array, dimension (LDAF,N)
• The block diagonal matrix D and the multipliers used to obtain the factor U or L as computed by SSYTRF.

🦋 LDAF 🦋

• LDAF is INTEGER
• The leading dimension of the array AF. LDAF >= max(1,N).

🦋 IPIV 🦋

• IPIV is INTEGER array, dimension (N)
• Details of the interchanges and the block structure of D as determined by SSYTRF.

🦋 WORK 🦋

• WORK is REAL array, dimension (2*N)

👑 Author 👑

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

Definition at line 120 of file sla_syrpvgrw.f.

👑 Author 👑

Generated automatically by Doxygen for LAPACK from the source code.

---

okay bye bestie 💋 this one is from LAPACK Version 3.12.0, and the footer path is /home/abui..._syrpvgrw.f(3). No date was sitting in that footer, so I'm not inventing one — we only report the facts here, periodt. 🎀✨