/home/abui..._syrcond.f(3)

🌸 NAME 🌸

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

This is the page for /home/abui..._syrcond.f(3), bestie, and it comes from the Library Functions Manual. 🦋

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✨ SYNOPSIS ✨

Functions/Subroutines

   Functions/Subroutines
       double precision function DLA_SYRCOND (uplo, n, a, lda, af, ldaf, ipiv,
           cmode, c, info, work, iwork)
           DLA_SYRCOND estimates the Skeel condition number for a symmetric
           indefinite matrix.

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💖 Function/Subroutine Documentation 💖

Okay so here's the full signature, and yes it's giving main-character energy:

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

DLA_SYRCOND estimates the Skeel condition number for a symmetric indefinite matrix. That's the whole assignment. 💅

🔥 Purpose 🔥

So what's the vibe? DLA_SYRCOND estimates the Skeel condition number of op(A) * op2(C), where op2 is determined by CMODE like this:

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 actual formula. ✨

🎀 Parameters 🎀

Every parameter, zero skips, because we don't do that here:

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

👑 Author 👑

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

Definition at line 145 of file dla_syrcond.f.

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🌈 Author 🌈

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💖 That's the whole page, bestie! It's from LAPACK Version 3.12.0, and the footer path is /home/abui..._syrcond.f(3). Go off and condition-number slay. 💅✨