SRC/dla_gerpvgrw.f(3)

💖 SRC/dla_gerpvgrw.f(3) 💖

okay so this is the SRC/dla_gerpvgrw.f(3) page from the Library Functions Manual, and bestie we are talking about DLA_GERPVGRW — yes, the double precision function itself. It's giving "I compute a reciprocal pivot growth factor" and honestly? iconic. 🫶

🌸 NAME 🌸

SRC/dla_gerpvgrw.f

✨ SYNOPSIS ✨

🧚 Functions/Subroutines 🧚

       double precision function dla_gerpvgrw (n, ncols, a, lda, af, ldaf)
           DLA_GERPVGRW

That's the function vibe check: dla_gerpvgrw takes n, ncols, a, lda, af, and ldaf, and it returns a double precision result. 💅

🦋 Function/Subroutine Documentation 🦋

   double precision function dla_gerpvgrw (integer n, integer ncols, double
       precision, dimension( lda, * ) a, integer lda, double precision,
       dimension( ldaf, * ) af, integer ldaf)
       DLA_GERPVGRW

okay so here is the full signature with all the types and dimensions laid out — no cap, she's official. ✨

🌸 Purpose 🌸

DLA_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.

bestie, that "much less than 1" part is the warning vibe: if the reciprocal pivot growth factor is tiny, the LU factorization stability could be poor, and then X, estimated condition numbers, and error bounds could be unreliable. Not me being dramatic — that's literally the page. 😭

🎀 Parameters 🎀

• N — N is INTEGER, and it's the number of linear equations, i.e., the order of the matrix A. N >= 0.
• NCOLS — NCOLS is INTEGER, the number of columns of the matrix A. NCOLS >= 0.
• A — A is DOUBLE PRECISION 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 DOUBLE PRECISION array, dimension (LDAF,N). The factors L and U from the factorization A = P*L*U as computed by DGETRF.
• LDAF — LDAF is INTEGER, the leading dimension of the array AF. LDAF >= max(1,N).

👑 Author 👑

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

Definition at line 98 of file dla_gerpvgrw.f.

💜 Author 💜

Generated automatically by Doxygen for LAPACK from the source code.

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okay bye bestie — this page is SRC/dla_gerpvgrw.f(3) from LAPACK, Version 3.12.0. That's the cute sign-off, and yes, she ate. 💅✨