DGBT01(3)

DGBT01(3) 💅

okay bestie, welcome to the Library Functions Manual page for DGBT01(3) — this one is literally the glow-up of /home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/TESTING/LIN/dgbt01.f and it’s giving “I reconstruct band matrices for breakfast” energy. ✨

🌸 NAME 🌸

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/TESTING/LIN/dgbt01.f

✨ SYNOPSIS ✨

🌈 Functions/Subroutines 🌈

       subroutine DGBT01 (m, n, kl, ku, a, lda, afac, ldafac, ipiv, work,
           resid)
           DGBT01

💖 Function/Subroutine Documentation 💖

   subroutine DGBT01 (integer m, integer n, integer kl, integer ku, double
       precision, dimension( lda, * ) a, integer lda, double precision,
       dimension( ldafac, * ) afac, integer ldafac, integer, dimension( * )
       ipiv, double precision, dimension( * ) work, double precision resid)
       DGBT01

🎀 Purpose 🎀

no cap, DGBT01 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. periodt. 🫶

🌈 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 DOUBLE PRECISION 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 DOUBLE PRECISION 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 DGBTRF. 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 DGBTRF 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 DGBTRF. 🔥
• WORK — WORK is DOUBLE PRECISION array, dimension (2*KL+KU+1). 💅
• RESID — RESID is DOUBLE PRECISION. 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 dgbt01.f. ✨

👑 Author 👑

Generated automatically by Doxygen for LAPACK from the source code. 💻

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and that’s the whole vibe! this page is from LAPACK Version 3.12.0 and lives at /home/abui...IN/dgbt01.f(3) — mwah 💋✨