SLA_GERPVGRW(3)

📦 version 3.12.0, in opensuse-leap 16.0

✨ SLA_GERPVGRW 💅

ok so bestie, this page is from the Library Functions Manual, and the star of the show is a little path that's honestly serving "my professor's file system" energy:

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

that's the NAME section, yeah. it's a .f file. it's giving Fortran. we love her. 🎀

🌸 SYNOPSIS 🌸

Functions/Subroutines

  • real function SLA_GERPVGRW (n, ncols, a, lda, af, ldaf) — literally just SLA_GERPVGRW, no further notes, iconic behaviour honestly

🦋 Function/Subroutine Documentation 🦋

real function SLA_GERPVGRW (integer n, integer ncols, real, dimension( lda,
    * ) a, integer lda, real, dimension( ldaf, * ) af, integer ldaf)

SLA_GERPVGRW — that's her. that's the function. 💜

🧚 Purpose:

ok so here's the tea, straight from the doc comment (!>):

!> !> SLA_GERPVGRW computes the reciprocal pivot growth factor !> norm(A)/norm(U). The norm is used. If this is !> much less than 1, the stability of the LU factorization of the !> (equilibrated) matrix A could be poor. This also means that the !> solution X, estimated condition numbers, and error bounds could be !> unreliable. !>

so basically: it computes the reciprocal pivot growth factor norm(A)/norm(U). and if that number is much less than 1? 🚩 the LU factorization of the (equilibrated) matrix A could be unstable, bestie. and that means the solution X, the estimated condition numbers, AND the error bounds could all be unreliable. not me finding out my answer was lowkey fake the whole time 😭

🍓 Parameters

  • N — N is INTEGER. it's the number of linear equations, i.e. the order of the matrix A. constraint: N >= 0. 🫶
  • NCOLS — NCOLS is INTEGER. the number of columns of the matrix A. constraint: NCOLS >= 0. slay, keep it non-negative.
  • A — A is REAL array, dimension (LDA,N). on entry, this is the N-by-N matrix A. the main character herself. 👑
  • LDA — LDA is INTEGER. the leading dimension of the array A. constraint: LDA >= max(1,N). don't forget the max(1,N), that's important fr fr.
  • AF — AF is REAL array, dimension (LDAF,N). these are the factors L and U from the factorization A = P*L*U as computed by SGETRF. bestie SGETRF did the work, AF is just holding the receipts. 💅
  • LDAF — LDAF is INTEGER. the leading dimension of the array AF. constraint: LDAF >= max(1,N). same energy as LDA, just for the other girl.

🌈 Author

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

a whole squad. group project but make it legendary. 🫶✨

💫 Definition at line 96 of file sla_gerpvgrw.f.

that's it, line 96, file sla_gerpvgrw.f. notes app says: found her. 🎀

👑 Author

Generated automatically by Doxygen for LAPACK from the source code. not a human, just a robot doing her little documentation thing. no cap. 🤖💖

ok that's the whole page bestie, you ate that reading session. ✨ and for the cute sign-off: this is LAPACK, Version 3.12.0, and the page lives at /home/abui..._gerpvgrw.f(3) — go forth and check your pivot growth factor. 🦋💜

📦 where this page comes from