SRC/sla_syrcond.f(3)

🌸 SRC/sla_syrcond.f 🌸

Okay so bestie, this is the SRC/sla_syrcond.f page from the LAPACK Library Functions Manual, section 3, and it's literally giving “Skeel condition number for a symmetric indefinite matrix” main character energy. Let's get into it 💅✨

✨ NAME ✨

• SRC/sla_syrcond.f

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🦋 SYNOPSIS 🦋

🧚 Functions/Subroutines 🧚

• real function sla_syrcond (uplo, n, a, lda, af, ldaf, ipiv, cmode, c, info, work, iwork) — SLA_SYRCOND estimates the Skeel condition number for a symmetric indefinite matrix.

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🌀 Function/Subroutine Documentation 🌀

💖 The full signature, no cap 💖

real function sla_syrcond (character uplo, integer n, real, dimension( lda,
    * ) a, integer lda, real, dimension( ldaf, * ) af, integer ldaf,
    integer, dimension( * ) ipiv, integer cmode, real, dimension( * ) c,
    integer info, real, dimension( * ) work, integer, dimension( * ) iwork)

SLA_SYRCOND estimates the Skeel condition number for a symmetric indefinite matrix. Iconic. Obsessed. 🫶

🎯 Purpose 🎯

The literal math tea is this:

SLA_SYRCOND estimates the Skeel condition number of  op(A) * op2(C)
where op2 is determined by CMODE as follows
CMODE =  1    op2(C) = C
CMODE =  0    op2(C) = I
CMODE = -1    op2(C) = inv(C)
The Skeel condition number cond(A) = norminf( |inv(A)||A| )
is computed by computing scaling factors R such that
diag(R)*A*op2(C) is row equilibrated and computing the standard
infinity-norm condition number.

No cap, that's the whole vibe check 💀✨

🧾 Parameters 🧾

• UPLO — CHARACTER*1. = 'U': Upper triangle of A is stored; = 'L': Lower triangle of A is stored.
• N — INTEGER. The number of linear equations, i.e., the order of the matrix A. N >= 0.
• A — REAL array, dimension (LDA,N). On entry, the N-by-N matrix A.
• LDA — INTEGER. The leading dimension of the array A. LDA >= max(1,N).
• AF — REAL array, dimension (LDAF,N). The block diagonal matrix D and the multipliers used to obtain the factor U or L as computed by SSYTRF.
• LDAF — INTEGER. The leading dimension of the array AF. LDAF >= max(1,N).
• IPIV — INTEGER array, dimension (N). Details of the interchanges and the block structure of D as determined by SSYTRF.
• CMODE — INTEGER. Determines op2(C) in the formula op(A) * op2(C) as follows: CMODE = 1 op2(C) = C; CMODE = 0 op2(C) = I; CMODE = -1 op2(C) = inv(C).
• C — REAL array, dimension (N). The vector C in the formula op(A) * op2(C).
• INFO — INTEGER. = 0: Successful exit. i > 0: The ith argument is invalid.
• WORK — REAL array, dimension (3*N). Workspace.
• IWORK — INTEGER array, dimension (N). Workspace.

👑 Author 👑

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

Definition at line 144 of file sla_syrcond.f.

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🌈 Author 🌈

Generated automatically by Doxygen for LAPACK from the source code.

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