TESTING/LIN/sgbt01.f(3)

🎀 NAME 🎀

okay bestie, this is TESTING/LIN/sgbt01.f — the page for the SGBT01 test routine. It's coming to you from the Library Functions Manual, and it's lowkey iconic 💅.

✨ SYNOPSIS ✨

🦋 Functions/Subroutines 🦋

       subroutine sgbt01 (m, n, kl, ku, a, lda, afac, ldafac, ipiv, work,
           resid)
           SGBT01

🌸 Function/Subroutine Documentation 🌸

👑 SGBT01 👑

   subroutine sgbt01 (integer m, integer n, integer kl, integer ku, real,
       dimension( lda, * ) a, integer lda, real, dimension( ldafac, * ) afac,
       integer ldafac, integer, dimension( * ) ipiv, real, dimension( * ) work,
       real resid)
       SGBT01

💖 Purpose 💖

SGBT01 reconstructs a band matrix A from its L*U factorization and computes the residual:

norm(L*U - A) / ( N * norm(A) * EPS )

where EPS is the machine epsilon.

The expression L*U - A is computed one column at a time, so A and AFAC are not modified. no cap, that's the whole point 🫶

🎀 Parameters 🎀

• M — M is INTEGER; this is the number of rows of the matrix A. M >= 0.
• N — N is INTEGER; this is the number of columns of the matrix A. N >= 0.
• KL — KL is INTEGER; the number of subdiagonals within the band of A. KL >= 0.
• KU — KU is INTEGER; the number of superdiagonals within the band of A. KU >= 0.
• A — A is REAL array, dimension (LDA,N); the original matrix A in band storage, stored in rows 1 to KL+KU+1.
• LDA — LDA is INTEGER.; the leading dimension of the array A. LDA >= max(1,KL+KU+1).
• AFAC — AFAC is REAL array, dimension (LDAFAC,N); the factored form of the matrix A. AFAC contains the banded factors L and U from the L*U factorization, as computed by SGBTRF. U is stored as an upper triangular band matrix with KL+KU superdiagonals in rows 1 to KL+KU+1, and the multipliers used during the factorization are stored in rows KL+KU+2 to 2*KL+KU+1. See SGBTRF for further details.
• LDAFAC — LDAFAC is INTEGER; the leading dimension of the array AFAC. LDAFAC >= max(1,2*KL*KU+1).
• IPIV — IPIV is INTEGER array, dimension (min(M,N)); the pivot indices from SGBTRF.
• WORK — WORK is REAL array, dimension (2*KL+KU+1).
• RESID — RESID is REAL; norm(L*U - A) / ( N * norm(A) * EPS ).

🧚 Author 🧚

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

⭐ Definition at line 124 of file sgbt01.f. ⭐

Definition at line 124 of file sgbt01.f.

💜 Author 💜

Generated automatically by Doxygen for LAPACK from the source code.

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okay that's the tea, bestie 🍓 This page is from LAPACK Version 3.12.0 — the footer doesn't show a separate date, so that's the version + source vibe: TESTING/LIN/sgbt01.f(3) 🫶✨