SGBCON(3)

SGBCON(3) — Library Functions Manual 💖

okay bestie, welcome to SGBCON(3), straight out of the Library Functions Manual — this is the whole page, no gatekeeping, periodt. ✨

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🎀 NAME 🎀

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

That's literally the whole NAME entry — it's giving “the file is the moment,” and honestly? Iconic. 💅

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✨ SYNOPSIS ✨

💫 Functions/Subroutines 💫

subroutine SGBCON (norm, n, kl, ku, ab, ldab, ipiv, anorm, rcond, work,
    iwork, info)
    SGBCON

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🦋 Function/Subroutine Documentation 🦋

Here's the full glow-up signature, bestie — types and all:

subroutine SGBCON (character norm, integer n, integer kl, integer ku, real,
    dimension( ldab, * ) ab, integer ldab, integer, dimension( * ) ipiv,
    real anorm, real rcond, real, dimension( * ) work, integer, dimension( *
    ) iwork, integer info)
    SGBCON

🎀 Purpose 🎀

SGBCON estimates the reciprocal of the condition number of a real general band matrix A, in either the 1-norm or the infinity-norm, using the LU factorization computed by SGBTRF. no cap, that's the whole assignment. 💖

An estimate is obtained for norm(inv(A)), and the reciprocal of the condition number is computed as:

RCOND = 1 / ( norm(A) * norm(inv(A)) ).

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🌸 Parameters 🌸

💅 NORM

NORM is CHARACTER*1

Specifies whether the 1-norm condition number or the infinity-norm condition number is required:

• = '1' or 'O': 1-norm;
• = 'I': Infinity-norm.

💅 N

N is INTEGER

The order 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.

💅 AB

AB is REAL array, dimension (LDAB,N)

Details of the LU factorization of the band matrix A, 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.

💅 LDAB

LDAB is INTEGER

The leading dimension of the array AB. LDAB >= 2*KL+KU+1.

💅 IPIV

IPIV is INTEGER array, dimension (N)

The pivot indices; for 1 <= i <= N, row i of the matrix was interchanged with row IPIV(i).

💅 ANORM

ANORM is REAL

If NORM = '1' or 'O', the 1-norm of the original matrix A.

If NORM = 'I', the infinity-norm of the original matrix A.

💅 RCOND

RCOND is REAL

The reciprocal of the condition number of the matrix A, computed as RCOND = 1/(norm(A) * norm(inv(A))).

💅 WORK

WORK is REAL array, dimension (3*N)

💅 IWORK

IWORK is INTEGER array, dimension (N)

💅 INFO

INFO is INTEGER

= 0:  successful exit
< 0: if INFO = -i, the i-th argument had an illegal value

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👑 Author 👑

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

📌 Definition at line 144 of file sgbcon.f.

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👑 Author 👑

Generated automatically by Doxygen for LAPACK from the source code.

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mwah 💅 — LAPACK Version 3.12.0, from /home/abui...RC/sgbcon.f(3). slay and goodbye 🫶