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

This is a Library Functions Manual page for /home/abui..._porcond.f(3), bestie — the manual name is folded in right here at the top, and the title is giving very much “LAPACK source docs but make it cute.” ✨

💖 NAME 💖

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

🌸 SYNOPSIS 🌸

💅 Functions/Subroutines 💅

• double precision function DLA_PORCOND (uplo, n, a, lda, af, ldaf, cmode, c, info, work, iwork) — DLA_PORCOND estimates the Skeel condition number for a symmetric positive-definite matrix.

🌟 Function/Subroutine Documentation 🌟

Okay so here's the full signature in all its glory, bestie:

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

DLA_PORCOND estimates the Skeel condition number for a symmetric positive-definite matrix.

✨ Purpose: ✨

The purpose is literally DLA_PORCOND 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)

Then 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. Linear algebra but make it slay. 💅

🎀 Parameters 🎀

• 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 triangular factor U or L from the Cholesky factorization A = U**T*U or A = L*L**T, as computed by DPOTRF.
• LDAF — LDAF is INTEGER. The leading dimension of the array AF. LDAF >= max(1,N).
• 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 139 of file dla_porcond.f.

👑 Author 👑

Generated automatically by Doxygen for LAPACK from the source code.

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