CGBT01(3)

🦋 CGBT01(3) — LAPACK Library Functions Manual 🦋

okay bestie, welcome to this Library Functions Manual page. This is the one and only CGBT01(3) — a LAPACK library functions manual page, and we're about to read it together like a group chat. No cap, every technical crumb is staying. 💖

🌸 NAME 🌸

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/TESTING/LIN/cgbt01.f

That's the file path, periodt. 🎀

✨ SYNOPSIS ✨

🫶 Functions/Subroutines 🫶

       subroutine CGBT01 (m, n, kl, ku, a, lda, afac, ldafac, ipiv, work,
           resid)
           CGBT01

💖 Function/Subroutine Documentation 💖

Here's the full typed-out signature, bestie — keep your eyes on the exact types:

   subroutine CGBT01 (integer m, integer n, integer kl, integer ku, complex,
       dimension( lda, * ) a, integer lda, complex, dimension( ldafac, * )
       afac, integer ldafac, integer, dimension( * ) ipiv, complex, dimension(
       * ) work, real resid)
       CGBT01

🎀 Purpose 🎀

CGBT01 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. Slay, no side effects. ✨

🌸 Parameters 🌸

• M — M is INTEGER. The number of rows of the matrix A. M >= 0.
• N — N is INTEGER. 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 COMPLEX 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 COMPLEX 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 CGBTRF. 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 CGBTRF 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 CGBTRF.
• WORK — WORK is COMPLEX 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 cgbt01.f.

💫 Author 💫

Generated automatically by Doxygen for LAPACK from the source code.

---

Okay bestie, that's the whole page. This cutie was built from LAPACK Version 3.12.0, and the footer path is /home/abui...IN/cgbt01.f(3). Stay slay, stay exact. 💖✨