DPOCON(3)

💅 DPOCON(3) — Library Functions Manual 💅

Okay bestie, welcome to the DPOCON(3) page — yes, that's the Library Functions Manual energy, and we are getting into it. 💖

🌸 NAME 🌸

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

This is literally the NAME line, no cap. It's a path, it's iconic, it's giving "LAPACK source file main character." ✨

✨ SYNOPSIS ✨

🎀 Functions/Subroutines 🎀

subroutine DPOCON (uplo, n, a, lda, anorm, rcond, work, iwork, info)
       DPOCON

🦋 Function/Subroutine Documentation 🦋

subroutine DPOCON (character uplo, integer n, double precision, dimension(
       lda, * ) a, integer lda, double precision anorm, double precision rcond,
       double precision, dimension( * ) work, integer, dimension( * ) iwork,
       integer info)
       DPOCON

🌟 Purpose 🌟

Okay so DPOCON estimates the reciprocal of the condition number (in the 1-norm) of a real symmetric positive definite matrix using the Cholesky factorization A = U**T*U or A = L*L**T computed by DPOTRF.

An estimate is obtained for norm(inv(A)), and the reciprocal of the condition number is computed as RCOND = 1 / (ANORM * norm(inv(A))).

The source comments wrap this whole purpose block in !> markers, but the math tea is exactly above. 💖

💖 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 order of the matrix A. N >= 0.
• A — A is DOUBLE PRECISION array, dimension (LDA,N); the triangular factor U or L from the Cholesky factorization A = U**T*U or A = L*L**T, as computed by DPOTRF.
• LDA — LDA is INTEGER; the leading dimension of the array A. LDA >= max(1,N).
• ANORM — ANORM is DOUBLE PRECISION; the 1-norm (or infinity-norm) of the symmetric matrix A.
• RCOND — RCOND is DOUBLE PRECISION; the reciprocal of the condition number of the matrix A, computed as RCOND = 1/(ANORM * AINVNM), where AINVNM is an estimate of the 1-norm of inv(A) computed in this routine.
• WORK — WORK is DOUBLE PRECISION 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.

👑 Author 👑

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

Definition at line 119 of file dpocon.f.

🫶 Author 🫶

Generated automatically by Doxygen for LAPACK from the source code.

---

Sign-off time: shoutout to LAPACK Version 3.12.0 and the footer path /home/abui...RC/dpocon.f(3) — that's the source/version situation, and no extra date was listed, bestie. 💜